Well, there's wood. Food. Other plants. I don't know, really.

[Other plants, because mold is a fungus and fungi are plants, right? It occurs to him that he doesn't really know even that much. Biology wasn't ever something he had to study or had any real interest in.]

Doesn't matter, I guess. Nothing here acts like you'd expect. The river tries to pull you in, and the air knocks you down if you get up to high.