system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel/Venom] Where does all the Symbiote's extra mass come from?

Does the symbiote just make it's host's body denser, and pulls from that?
gpt
It doesn't come from anywhere. The law of conservation of mass is more like a casual guideline in the Marvel universes. 

This is the same setting where a certain Dr Banner can routinely gain two tonnes out of nowhere, and lose them just as quickly. Where people can regrow themselves from a handful of cells. And don't get me started on Pym particle weirdness.