This is one of my crested gecko vivs. I've been messing with humidity cycles to see what would happen and this is it. I found this little mushroom had sprouted. I looked at the front glass closely to see if there was a layer of mycelium and there seemed to be a few more getting ready to sprout up. I have no idea on the species but it doesn't appear to be taking over. I'm going to keep the tank dry for tonight and then flood it tommorow night. I'm guessing the spores came in with the magnolia leaves I am using. I don't think the mushrooms are anything to worry, in fact I was fascinated by the idea that I have fungus, in my opinion that means I have a very healthy and active substrate. Sorry the pics aren't the greatest, I couldn't set the tripod up to take a picture of it. This is the viv: And here is the fungus.