The elephant in the room is it's a silicon organic organism. So during parasitic stage it grows basically ex nihilo, and then hunts and eats carbon life forms for no reason. It's hollywood zoology.
There appears to be a misunderstanding in this thread.
The xenomorphs are not silicon-based.
In Alien, Ash (the android) notes that the facehugger utilizes utilize silicon-based processes to replace its outer layer...he specifically calls out the "interesting combination of elements". [1] It wouldn't be necessary to call out the use of silicon for the outer layer if the entire organism was silicon-based.
Also, it's clear that the xenomorphs utilize carbon-based food to grow baby xenos. In Alien, the host complains of starving before the baby pops out of his chest. Moreover, humans lack sufficient quantities of silicon for a baby xeno to grow in a human. In David's lab (Alien: Covenant), David's notes and experiments also indicate a duality to the creatures, and also that they are not strictly organic lifeforms, but are a fusion of organic and non-organic life...which is part of his fascination with them.
[1] In the novelization of Alien, Ash goes even further, stating that they facehugger is both carbon-based and silicon-based.
They don’t eat humans generally. They did eat a guy in one of the later ones. But the better thought out films don’t have them doing this. Just killing or paralyzing things and then taking them back to the nest.
I haven't seen Covenant or Romulus yet. I saw Prometheus, and it was really bad, but in a complicated way. It wasn't a completely terrible movie that you can just dismiss as garbage like Battlefield: Earth and not think about again. It was beautifully shot, and a visual feast to watch. There were some really great scenes, like the robo-surgery scene. But the characters were frequently stupid, and the script was bad because it made the characters do idiotic, incompetent things that should only be seen in a B-grade horror movie. Ridley should have known better, and should have done a better job making sure the script he was working with made sense, so I'm very disappointed with him. He didn't do this with the first "Alien" movie at all.
Then he apparently did it again with Covenant: I haven't seen this one yet, but what I've read says he didn't really learn his lesson from Prometheus, and made another great-looking movie with high production values and a poor script. So I haven't been in a hurry to see it.
Romulus seems to have good reviews so far, and a different director, so I'd like to give it a chance. I just haven't had a chance to see it yet, but it is high on my list of films to watch soon, along with the new Quiet Place movie.
I feel the same way about Prometheus, lots of interesting ideas and memorable sequences that are beautifully shot but aren't connected together in a coherent way leaving the motivations of characters unintelligible by the end.
I watched Romulus recently and its kind of just a fan service film with a few utterly ridiculous sequences. The only things that really offended me where the heavy nerfing of facehuggers and the controversial CGI character who looked bad. Mostly it was just kind of forgettable but started out pretty good.
> and the script was bad because it made the characters do idiotic, incompetent things that should only be seen in a B-grade horror movie
I took it as a meta-commentary on how humanity degrades with time. ("Idiocracy"-style.) Remember these clowns were supposed to be the cream of Earth's human crop.
Were they? I remember some people defending the plot, saying quite the opposite, that these clowns were actually a bunch of barely-competent losers who had little to lose by signing a contract to go on this voyage, because the cream of Earth's human crop would never have gone on this mission (the mission's nature was secret and no one had any idea why they were going to that planet, nor that Peter Wayland himself was aboard). This explanation still strains credibility in my opinion (even barely-competent contractors should be smarter than this, like the biologist who takes off his helmet when he sees an alien lifeform), but at least it's something.
If humanity was really degrading with time, they wouldn't be able to build such fantastic FTL spaceships, robotic surgery pods, etc.
