It could be developing a necrotic area (rub your finger around the hole and see if it crumbles at the edges) or it could be splitting. I remember a thread a couple years ago on another forum about a toadstool splitting from the middle, I had never heard of it before, but they provided photos and it is possible.
Ok I did this, very slimy and I guess because the clown hosts it a lot it didn't retract either, weird huh. It didn't crumble, felt very smooth, LOL
it will be cool if it does split, I guess I don't blame it, it's pressing up against the glass. The leather is attached to two pieces of live rock, it is going to be really interesting getting it out of the tank, we plan on filling a rubbermaid that's why I had asked on the other post about acclimating, would I be able to take some of the water from the tank out and just directly put the toadstool in with out going through an acclimation thing since it's the same water? I really hate doing this, this tank has been so good for us, I don't want to wreck it but we have no choice.
Thanks again Kevin for always being there to answer our questions you and Aaron and all that help us on this site are great!