Is this Mycelium dangerous? First of all, what is it? Here's the story of how it began. I have a moss terrarium starting in a jar. I also intended to eventually put some leafy growth in as well, but fertile soil is required for that, so for a month or two, I've been putting dead plant cuttings and other things in it to decompose and make the soil a little more rich. Anyway, one day I noticed a cotton like structure emerge, and suddenly, the day after the next, it had filled the entire jar. Up to the lid. Is this dangerous to breath in? It has little blackish brown specks which might be spores of some kind. Should I dispose of this monstrosity that I've accidentally created, or is it relatively safe to keep in a glass terrarium? Originally by u/69MalonesCones420 on Reddit: https://tinyurl.com/25vogkxf