Hairy Mushroom

[edikpok]

I have had this hairy mushroom for almost half a year now. I suddenly noticed 3 das ago that a hole appered in the centre of it , where the mouth used to be. It looks shrunken and doesn't open as it used to but it is sill alive. All other corals and fish in the tank are doing great. What could hav caused it? anything I can do to help it survive this trauma?

Thanks!