What is growing under my toadstool? Help ID

[danny325is]

I have some whiteish Tubes growing from under the frag plug on my Toadstool. My Toadstool is not happy right now because there is Prazipro in the tank to fight some potential Fluke issue. Also it looks like the Toadstool is moving off the center of the plug (can they do this?). I have had this frag for about 3 months or so now. all help is appreciated.

 

[JGT]

Sponge. Yes they can move, albeit slowly if not happy in their current location.