I just saw Ridley Scott's “Prometheus” and I’m still confused about how the black liquid works. Can anyone elaborate on what its function was and the mechanism by which it operated?

I surmise that it was meant as a biological weapon (something they mention in the movie at various points), that was released prematurely and infected the developers (the “Engineers”, so named by the characters in the movie), but I still don’t understand the exact mechanism by which it functioned.

From what I can tell, it infects a host, whereby it either:

  • kills them
  • mutates them into a killing zombie, or
  • uses the host to gestate another more complex organism in the host or anyone that the host comes in contact with.

Can anyone elaborate under which conditions these symptoms arise or whether they’re even correct in the first place?

Some examples of the black liquid’s various effects are:

  • When the scientists find the pile of dead engineers. Presumably they were infected and died from their infection (but perhaps this was not the case and they were killed from a quarantine protocol?).
  • When trying to revive the head of the decapitated engineer, it burst
  • In the opening scene, an engineer is seen drinking the black liquid which then proceeds to destroy his body (though this may be a different black liquid, not meant as a weapon but meant as a life-seeding operation? See here).
  • Fifield (the geologist played by Sean Harris) came back to terrorize the crew of Prometheus after he had his face doused in acid and had presumably been exposed to the black liquid (i.e. he became a “killing zombie”).
  • Dr. Charlie Halloway (played by Logan Marshall-Green) “impregnated” Dr. Elizabeth Shaw (played by Noomi Rapace) with a squid-like alien after being infected himself and having intercourse with Dr. Shaw (i.e. the black liquid giving rise to a more complex organism).

In addition, there is some evidence that the black liquid alters the organism it infects to produce a more complex “seeding” organism. For example, when the chamber with the giant statue of the Engineer head is (where they find the head of the decapitated Engineer), we see earth worms writhing in the soil. Later, in the same room, we see a snake-like alien come out of the pools the black liquid that kills Millburn (the biologist, played by Rafe Spall) by going down his throat and presumably planting another organism for gestation.

In the same vein, we see a small writhing worm-like organism coming out of Dr. Charlie Halloway’s eye when he was inspecting himself in the mirror and when he first noticed his infection.

From the original Alien canon (both from the movies and comic) it’s been clear that the face hugger is meant as a “bootstrap” organism whereby it implants a seed organism into the host which then uses the host’s DNA to better adapt to its environment. This can be seen in Prometheus as well after an alien bursts from the revived Engineer’s chest in the final scene.

Though the facility to create more eggs (or face huggers) was never explicitly mentioned (to my knowledge), from the fact that there was a queen alien in the “Aliens” movie I took the aliens to be more ant-like, where, given the need, an alien could differentiate itself and become a “queen” alien to then lay eggs. I’m unclear as to how this fits into the information from “Prometheus”.

I am tempted to think that it is sloppy story-telling meant more for effect without regard to consistency, but out of respect for Mr. Scott I would like to give him the benefit of the doubt and see if there is a consistent set of rules by which all the evidence above makes sense.

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    I like this simplified Prometheus Species Origin artwork created by Carlos Poon: 9gag.com/gag/4430817 It's funny, yet, so true in explaining things.
    – spong
    Jun 12, 2012 at 17:11
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    Since the two unlucky fellows in the canister room didnt produce the xenomorph, I think we can assume the "worms" mixed with the DNA goo didn't pan out as we'd expect. Jun 21, 2012 at 18:02
  • There is a thing you have not thought about - there is a scene where an Xenomorph Queen is calved inside the ship, so I think the black liquid is a superevolutive weapon made to make xenomorphs as a final stage.
    – user7569
    Jul 4, 2012 at 6:45
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    “I am tempted to think that it is sloppy story-telling meant more for effect without regard to consistency, but out of respect for Mr. Scott I would like to give him the benefit of the doubt”. The final Prometheus script was written by Damon Lindelof, co-showrunner on Lost, so if we’re looking for someone to blame for “sloppy story-telling meant more for effect without regard to consistency”, I think Ridley’s in the clear :) Apr 21, 2013 at 10:23
  • 1
    Best ask the X-files which is where they stole it from. Apr 22, 2013 at 13:44

8 Answers 8


I think there are actually two different black liquids at play, and a third unknown pathogen.

Black Liquid #1

The first liquid is seen at the beginning of the movie. An unknown engineer is dropped on earth and consumes the black liquid, which immediately begins to breakdown his body. His infected cells/DNA go on to seed earth and begin human evolution. This liquid appears to be used by the engineers to spread themselves across planets.

Black Liquid #2: Bio-weapon

The second black liquid was found in canisters in a sealed containment room on LV-223. After opening the room, the liquid became active. It appears to alter an organism's DNA, turning the organism into a weapon.

Remember the worms crawling around in the ground? After a few hours of exposure to the black liquid, they became very powerful, very dangerous reptile-like creatures. One of the mutated worms kills Milburn and in the struggle, Fifield is burned and exposed to the black liquid. Several hours later, Fifield appears at the Prometheus, obviously enhanced: he kills several crew members before the rest of the crew manages to kill him.
Holloway was the first to be infected by the black liquid. Shortly after being exposed, he had sex with Shaw. Before having sex, however, it's made clear that Shaw is infertile and unable to have children. Yet, after Holloway's death, David discovers that Shaw is pregnant.

It's my theory that Holloway's sperm, infected by the black liquid, grew into its weaponized form inside Shaw. Shaw successfully removed it, but it continued to grow until it became a giant facehugger.

Unknown Pathogen

The unknown pathogen is never actually seen, but its effects are. At some point, about 2,000 years before Prometheus arrives on LV-223, some kind of pathogen kills all but one of the engineers. When Shaw, et. al., are studying the severed engineer head, they are able to reanimate it and the pathogen. This causes the head to explode. Very nasty.

It would seem from the holograms and piles of bodies seen in the engineer facility that this pathogen struck quickly. I imagine it was bio-engineered by the engineers, and somehow escaped containment. By the time Prometheus arrives, this pathogen is no longer present on LV-223, since the last engineer never becomes infected.

  • 3
    Why do you assume the planet in the first scene is Earth? Jun 7, 2013 at 0:08
  • 1
    @splattered bits Why answers are visible on mouse hover event only?
    – mujaffars
    Mar 26, 2015 at 15:32
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    @mujaffars They contains spoilers for the movie. Mar 27, 2015 at 21:53
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    +1 The idea that there are three different substances involved makes far more sense than anything I could come up with when watching the film myself.
    – Ixrec
    Aug 8, 2015 at 20:19
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    @splatteredbits Anyone reading the question must be prepared to find spoilers in the answer.
    – Lexible
    Oct 25, 2017 at 22:49

This is not my personal theory. The links below are to interviews with Scott and various essays based on those interviews. As silly as it may seem, this is what Ridley Scott claims to have intended.

The Mystery of Sacrifice Did It

The Goo Giveth and the Goo Taketh Away: When it encounters altruism and self-sacrifice (the Engineer voluntarily giving his life at the start of the film), it begets new life. When it encounters selfishness and greed (just about everybody else in the film), it becomes an agent for the destruction of life.

Why does it work that way?

Prometheus doesn't always make a lot of sense at a logical/realism level, but it's much more comprehensible at a symbolic level.

The Engineers (space jockeys) not only seeded life on many planets including Earth, they later sent back... well, Jesus. That's why the film makes such a big deal over the "2000 years" thing: Jesus was an Engineer, we killed him, and the Engineers were prepping to use the Goo to punish us.

So the Goo is... some kind of representation of God's mercy and wrath? It's not exactly clear, but probably something like that. You'll see a lot of other Christlike imagery in the film if you look for it, including the three cruciform poses as the ship crashes, and the Engineer version of The Creation of Adam.

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    Yes, I know this seems a bit silly. I wish I had a better answer for you, but this is what Scott gave us. It does explain why the film feels like it's got a gap in it: the gap is shaped like Space Jesus.
    – BESW
    Jun 5, 2013 at 10:35
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    Man the livejournal piece was an eyeopener, I mean how do you analyse this at such depth, wow wow! Jun 7, 2013 at 14:31

First of all at the beginning of the movie the 'engineer' is wearing a robe rather than the suit as seen in all other engineers. This suggests that there are 2 beliefs among these engineers. Much like there are multiple religions here on earth. These 2 beliefs (based on the actions of the engineers) are that:

  1. The Human-loving engineers believe that humans are made for a purpose and a reason which is what the team is hoping to find out. This would explain why the first engineer that we see was clearly sacrificing himself using the "black liquid" to make human DNA. This would also explain the change in clothing (robes rather than equipment looking suits). The ship in the background also is different to the one seen in the movie, possibly a personal transport, and as seen in the behind the scenes picture of the elder engineers, it is possible that the younger healthier engineers are sacrificed.

  2. On the other side the Human-hating engineers believe that the humans are a failed science experiment and should be destroyed for further experimentation. The change in clothes from robes (usually associated with the church) to the military looking equipment suggests that the engineers on the C-shaped ship are military personal seeking out the UFO shaped ship to destroy the human life they are creating. It is also most likely the "black liquid" seen on this ship is a variation of the one seen at the beginning of the movie. It appears to be a bio-weapon to alter the DNA to create a super-being by strengthening the host DNA. The dead (possibly soldier) engineers on this ship were most likely contaminated with the bio-weapon liquid and were self-eliminated. However, there is a possibility that these suits are merely space suits, but I believe this is unlikely because at the beginning and at the end that an engineer goes outside without wearing the mask seen on all other suits.

Concluding I believe that there is a war going on between the engineers, which isn't hard to believe considering all the war and violence on Earth, however this seems to be a more technologically advanced war being fought on different planets such as LV-223 (Prometheus) and possibly LV-426 (Alien).

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    Ironically both group use the black liquid to create life through destruction. Sacrificing themselves to create life on earth or infecting humans to create monsters. Aug 27, 2012 at 17:00

The engineers may have been running from one of themselves, infected by the black liquid/weaponized DNA (the head that exploded showed signs of the infection in its scalp).

The geologist and the mutated worms are our only on-screen depictions of pure black liquid exposure, and it would seem to have the effect of making a species far more powerful and aggressive, "magnifying" its native DNA.

The pile of dead engineers with burst chest cavities seems to herald the alien life cycle we're familiar with, but perhaps the bursting bodies are simply the last stage of infection as demonstrated by the exploding head.

The worms having a similar "biological imperative" to the aliens we've seen, regarding body entry/feeding and exit, might suggest that the sample David had acquired had mingled with some of the earthworm DNA before being ingested by Halloway, thus creating a human-worm-alien toxin soup in Shaw's womb. Her "child" then exhibited the aggressiveness of the weaponized DNA (black liquid), the wormlike physical traits & cavity entry of the worms, and the ability to reproduce "stolen" from the human lifecycle due to its exposure to Shaw's womb.

At any rate, the black liquid weapon seems extremely unstable, and highly reactive to any DNA it encounters. I suspect the "facehuggers" were an unplanned side effect of the exposure to the earthworms and the human reproductive cycle. At the very end of the film, we see new life created when this creature then births anew through the body of the engineer, creating the first alien queen.


Many years later, I finally came across what I consider a thorough analysis of the film by Comic Book Girl 19's Epic Review: Prometheus. She has a nearly 45 minute long video describing most of the points I listed and many more. I'm going to pick out a few of the points that are relevant but I encourage anyone interested to watch the whole 45 minutes as Comic Book Girl 19 does an excellent job of dissecting the movie and I won't be able to really do it justice here.

My main concern was what did the black liquid actually do. Comic Book Girl 19 goes on at length about how the original script, written by Jon Spaights, was changed drastically by Damon Lindelof. I think Lindelof's involvement is key in understanding the mechanics, or lack thereof, of how the 'black goo' worked.

This looks to be answered most succinctly by Damon Lindelof in an interview with Ridley Scott and Damon Lindelof by slashgear.com:


So there's a speculative part of it, so the question becomes "what does the black goo do?" That is the question that you're supposed to be asking coming out of this movie.


(emphasis mine)

Under a competent screen writer, the above could be taken to mean that there was some consistency behind the mechanism of how black goo worked but that the audience was required to put thought into discovering what it was. Unfortunately, considering the many blunders of the film and Lindelof's track record for invoking common tropes, I have little faith that Lindelof or Scott have any real understanding of what the black goo did.

Given the carelessness of the writer, I take the above quote to mean that they deliberately did not have a consistent idea of what the black goo did. To me, this unfortunately confirms my fears that this was lazy screenwriting and sloppy storytelling.

There seems to be a vague consensus that the black goo acts a 'mutagen'. Some of the cut scenes shed light on this:

  • In the original script, the black goo consumed by an engineer at the beginning of the movie turned into a scarab-like thing, bit a woman whose DNA then started to mutate.
  • In the original script, the engineers were working on multiple types of 'aliens', which could have been an explanation for the diversity of reactions (and resultant aliens) to the goo. The goo could look the same but actually have different functions, depending on how it was engineered.
  • In a cut/altered scene, after Fifield gets his face doused in black liquid comes back not as zombie but as a mutated 'Alien' like thing.

To me, the more telling reasons for the lack of cohesion and consistency is better explained by the following:

The combination of lack of oversight from Scott and the lack of attention of Lindelof created a movie without rigor.

Prometheus 2 is presumably due out at some point. I will happily accept that my conclusions are wrong if the sequel somehow sheds more light on the subject.

  • of course, the goo might not be all the same - each pot might have a different "version" or batch of the stuff. Like a bio experiment, the chamber didn't contain lots of final product, but all the old attempts at getting it right. Nevertheless, its not real... just a story :-)
    – gbjbaanb
    Oct 5, 2015 at 12:44
  • The computational capabilities of that goo must be tremendous. It mutates the DNA without killing the host and with getting some meaningful organism out at the end. That can only mean it runs whole-host trial-and-error simulations, billions and billions of them, and test the simulated organism against a simulated environment, until it finds something acceptable, while you wait! The whole-host will be fully "alive" in that simulation, too. Sequels just write themselves. May 23, 2020 at 13:15

The black goop appears to have properties such that different species, i.e. Engineers, humans, etc, react to it differently.

As you mention,

the black goop triggers a transformation in the Engineer such that he disintegrates and spreads his DNA widely, providing the basis for life.

However it's definitely plausible that a substance can affect different species in different ways as we have many many examples on Earth - pools of acid that support bacteria that would dissolve other creatures, leaves that can sustain animals who eat nothing else but would kill us if we ate too many, etc.

In this case, it appears that the black goop provides the basis of the

Alien metamorphosis, as it oozes out from the Alien "eggs" and we see the proto-facehuggers attacking from it and using it as a home environment.

When humans are exposed to it

they become infected by an Alien in some form (worms in Holloway's eyes, indirect exposure resulted in an Alien fetus in Shaw).


According to me, the problem starts at question, what killed Engineers. It is showed that they were running, from what?

Also there is no prove that the thing to which Fifield (the geologist played by Sean Harris) turned would became also from Dr. Charlie Halloway (played by Logan Marshall-Green). We also saw that after the intimate act with Dr. Elizabeth Shaw (played by Noomi Rapace) he saw something in his eye, something what was moving and looked like a small worm to me.

Why would Engineers put the black liquids forms into the chamber if it would be so dangerous for them? They were running also to that chamber.

According to me the "DARK LIQUIT" project was infected by Allien DNA and that is what killed them one way or another. We should keep in mind that Engineers died 2000 years ago, so there is a plenty of time to mutate. Maybe this is not the origin of Alien, maybe this is just let's say the first encounter with humans.

So to answer the question. The "dark liquid" manipulates with DNA, but obviously, the Alien DNA has it own manipulation method. The Aliens infected the "dark liquid". That turned the small worms in the chamber ground to big breaking-arms creatures. That is how the small worm appeared in the Dr. Charlie Halloway eye and why Dr. Elizabeth Shaw had to make that very nice surgery on herself. Whatever was the purpose of the "dark liquid", it was altered by Alien DNA. The "dark liquid" has the ability to destroy DNA, however Alien one has the ability to survive in any conditions. Put these together and you have a movie of many questions : D

  • Interesting theory. This would make the liquid drank by the Engineer at the beginning the same as that discovered on LV-223 by the humans, just that the version the Humans found was infected/altered by aliens.
    – Xantec
    Jul 5, 2012 at 15:34


This is what I think:

The Engineers must have two separate beliefs when it comes to humans; the planet they are on in Prometheus (LV-223) is not the home planet of the Engineers. This makes me assume that the Engineers that oppose the humans left their home planet to begin work on destroying the humans while staying safe and hidden on this new planet. The black liquid must be developed from the original fluid that the robed Engineer drinks to create humans or it might even be the exact same liquid from the beginning because that liquid affected the DNA of the Engineer that ingested it, so it must have been designed or derived from that very liquid. It must have been the human loving original Engineers that were traveling to earth just checking on the humans to ensure nothing was going to happen to them. This also makes me think that maybe an Engineer who was really trying to help the humans disguised himself as one of the human hating militarized Engineers to sabotage the work they have done to help save the humans, and once he did that, maybe the original Engineers felt earth was safe so they stopped visiting.

Once the militarized Engineers had finished work on the liquid, something had to have happened and the liquid must have been released right before they were about to leave for Earth. The ship was full of the cartridges and was ready to destroy the humans, but it never left, sabotage maybe?

This is what I think happened: the Engineers didn't realize the potential power that the liquid had, and so they were careless. Maybe they thought it would only affect humans negatively so they didn't quarantine it. ; I don't think exposure to the liquid themselves is what killed them , they already knew that when they themselves were exposed to it, it only created humans, so maybe they didn’t feel it was dangerous. I think that the liquid was exposed to the worms and made those Hammerpedes that killed Milburn and Fifield on a massive scale. I think it was the Hammerpedes that killed off the Engineers, because there had to have been a lot of worms in the Engineers ship as we saw many were still there when the humans got there, so it was an environment that they thrived in. This would explain why all the dead Engineers had a burst chest, because when the Hammerpede left Milburn, it just burst out. The Hammerpedes that killed the Engineers must have run out of food and eventually left or died off. It was 2000 years later that the humans showed up, so that explains why the infected Hammerpedes weren't still there. So when the Engineers failed, they must have known that waiting it out was the only defence, so that is why they went into their life pods.

Since the black liquid was re-designed or just used to destroy, you can assume that the Engineers knew that when humans are exposed to it, they just grow strong and aggressive and try to kill each other. This would explain why Fifield attacked his crew, and why the Hammerpede was aggressive. Fifields whole face was exposed to the liquid, and he didn’t consume it. Charlie only had a drop, and he consumed it, so maybe that is why his transformation took so long, giving him time to have sex with Shaw before he knew he was sick. Charlie’s effected DNA must have been in his sperm and when the sperm fertilized Shaw's egg, a whole new species was born: a Trilobyte that we the fans call "Cuddles" the giant face hugger. Cuddles would have surely burst out of Shaw, but she did the surgery and got it out prematurely, saving her life. So now when Cuddles the Trilobyte destroys the last remaining Engineer on the ship, it must have used it to mate, which creates the Xenomorph.

Basically, these are my thoughts simplified: Hammerpedes are the worms that are infected by the black liquid, Hammerpedes killed the Engineers. The Engineers are the giant white aliens that the humans want to talk to. Trilobytes are the giant face huggers you see at the end (the one Shaw gave birth to). Xenomorphs are the double jawed aliens from all of the Alien movies.

      Black Liquid + Engineer = Humans
      Black Liquid + Worm     = Hammerpede (Hammerpedes kill off Engineers)
      Black Liquid + Humans   = Infected Human
    Infected Human + Human    = Trilobyte (By the act of mating)
         Trilobyte + Engineer = Xenomorph (By the act of mating)

The black liquid is a bio-chemical weapon that the Engineers develop from the original liquid that created humans, to destroy the humans. The Engineers are divided into 2 colonies, as is witnessed with the first Engineer being robed and having a Disk shaped ship; the other Engineers are militarized with armor and C-shaped ships. Black liquid accidentally infects worms on LV 223, Hammerpedes then destroy the Engineers. Humans come in and get infected, and spread the infection through mating, creating new species (Trilobyte); that new species mates with The Engineer making yet another new species (Xenomorph).

  • You might want to use spoiler tags (start line with >! ) on relevant material
    – The Fallen
    Oct 14, 2012 at 3:44

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