This morning when I went out to the garage, I noticed a new addition to my Tegu's cage. A toadstool had sprouted?? It had a white stalk with a black/gray/silver top. I am using a sand/soil mix for substrate, Temps 75-90, basking 105-115, humidity 65-85. It is a 8x3.5x3 wooden enclosure with double drop down doors. Any idea on what this is that sprouted and if it is harmful?? Also any way to prevent it from growing again?