This question made me think about what we know about the Xenomorphs. Namely, that they have exoskeletons. How is it the Predators have an exoskeletoned creature's inner skull in their trophy case?

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    It could be the exoskeletal remains. It is possible the remains lose their color over time. Or they could have been treated with a surface treatment to prevent their decay, so they are aesthetically similar and pleasing to the Predator eye. Jun 5, 2013 at 19:33
  • @Thaddeus This would be worth a proper answer, I think.
    – BESW
    Jun 6, 2013 at 10:49

2 Answers 2


We know that the Aliens have a hard exterior, but that alone does not prove that the creatures have no internal skeleton. Armadillos and tortoises sport hard body armor but also have endoskeletons. The insectile appearance of the Aliens suggests an exoskeletal structure, but scaling problems would cause a creature to collapse under its own weight unless we posit the existence of unreasonably strong materials.

So I believe the initial premise is wrong: Aliens have endoskeletons, not exoskeletons. The hard exterior is simply armor.

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    There's nothing that keeps them from having an endoskeleton AND an exoskeleton. Though it would be fair to characterize an exoskeleton as armor, I suppose.
    – Jeff
    Jun 6, 2013 at 17:20

There's an unspoken assumption here: that creatures with an exoskeleton don't also have an endoskeleton. That may be true for creatures on Earth, but Xenomorphs did not evolve on Earth. Given their extraterrestrial origin and evolution, I think it perfectly reasonable to think that Xenomorphs could have an endoskeleton in addition to their exoskeleton.

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    It's not even entirely true for Earth - Armadillos functionally are almost exoskeletal, and have a full endoskeleton as well. Turtles hybrid skeletons are a mixture of endo- and exo-skeleton.
    – aramis
    Jun 8, 2013 at 9:41

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