That is the perfect Alien. It looks like one of Giger's paintings coming alive. I loved the movement pattern the Alien in Alien did, especially with its arms, during that specific scene - truly haunting! I also love all the weird multitude of noises Kane's Son made instead of the almost monotonous screeching and hissing, and later on the roaring and growling, from the sequels...
That is the Grim Reaper. Seemingly cold and dead both on the inside and the outside, yet full with the most sinister form of curiosity and cunningness. You can totally see why Ash envied it and got infatuated by this creature - it's like a machine, just like an Android, silicone based, but it has a "soul"... the difference is that the "soul" of this being wasn't created by humans, like Ash's constructed persona, hence why he envied this creature that is so pure in his eyes, which were full of contempt to us humans... In the messed up computer brain of his he probably "wished" that he was like Kane's Son - invulnerable, inhumane and omnipotent, hence the misanthropic "the perfect organism" speech.
If they'll bring back this nightmare in the prequel, I'll be a happy clam!
