 In _"Blue Planet, The" (2001) (mini)_ (qv),  David Attenborough (qv) said the Alien monster was modeled after  the Phronima, a creature spotted by submersibles at great depths.  Its only an inch long, mostly transparent, and it looks like a  shrimp with head, eyes, jaws and teeth just like the  H.R. Giger (qv) monster.