At the end of Prometheus we get to see the famous alien of Alien.
It's born through the following steps:
David (the android) infects Dr. Holloway with the black liquid
Holloway impregnates Dr. Shaw with a creature that grows to be a ginormous facehugger
The ginormous facehugger implants an egg into the chest of one of the Engineers
The egg hatches into an alien
Is the alien as we know it the inevitable consequence of the black liquid, or would a different type of creature have resulted if a different bunch of individuals / species were involved in the process.