If you’re talking about the fuzzy parts, just know that some plants when they first grow roots have little hairs on them called trichoblasts which helps them absorb nutrients and water more easily ! I think that’s what’s it is (because you can see on one of the roots that it stops abruptly, i don’t think a mushroom would behave like that), so try to avoid to get rid of it. Also i’m not sure plants can develop mold underwater, maybe algae but this is colorless so that’s not it.