system
Given the following post, respond as if you're commenting on Reddit:
human
[ALIEN] What did the alien eat in order to grow so large?

It was nine inches tall, and a few hours later it's nine feet tall. Plus, it must have drunk a lot of water to have so much slime dripping from its mouth.
gpt
In the text record of the Nostromo incident the crew discovers that the alien has raided the ship's food storage lockers soon after it burst out of Kane.    


Considering how much resin, slime, acid blood and other unusual stuff the alien's body makes it may well be able to eat and process things we don't see as food as well.