Thank you. I didn't even know about the technical manuals. I think you maybe right about the needing or used some form of acid.In ALIEN pre-production and novelisation, there are notes about how the growing xeno ripped into the ships food supply and ransacked it by tearing into it from an airduct running behind it.
That also made the time out of hypersleep so much shorter for the crew having to stay up and find the beast.
I am not a chemistry anything, but I always equated the alien's ability to eat human food to be that it used acids just like we do.
Just because it has one kind of acid for defense does not mean that's the only kind it could possess / use.
We have weak stomach acids and stomach lining that can take them even if that is bad news for the rest of us.
The xeno is able to grow and contain some strong acids - so should be even easier.
Now... the chemistry of HOW the xeno could make use of human food after eating it ... or human brains after it (apparently) prefers to eat them?
That will be a mystery ... which the Colonial Marine Technical Manual lampshades really well as a transcript of some scientists arguing over that exact topic.
I thought the same thing. that they used humans as incubators but we're interested in minerals. so It must of been said somewhere.I might have dreamt this, but I thought I read somewhere that Xenos might in fact eat minerals; them being a silicon based lifeform (as opposed to a carbon based one), and all. That's why, as I understood it, they develope metal teeth (in some versions) and hard, metalic black exoskeletons. So, if that's true, the Facehugger onboard the Nostromo must have eaten metals off of the walls of the ship, somewhere down in the bowls of the Nostromo, eventually growing into the full beast.
That said, there's no reason why they can't also eat carbon based stuff like people, for those nice oils and calories and whatnot that we're so deliciously full of. (Just like how we, humans, eat minerals in several ways, many of which are entirely necessary for our carbon-based forms to exist).