possible parasite on my mushroom rock

[bwoodward0012]

wondering if anyone has seen something like this (no picture): have a 1 or 2 lb piece of live rock covered in about 15-25 fuzzy green shrooms. Was looking at it earlier and noticed what apeared to be a hole in the bottom of one of the mushrooms that was closed up. the hole had something moving in it and what appeared to be sweeper tentacles coming out of it. we grabbed the tweezers to see if we could get it but only got a few of the tentacles as something retreated into the hole. started digging at the hole and pulled off a hard chunk of something out of the hole. moved the mushroom a little and reallized there was a tube like structure coming out of the rock and the base of the mushroom. Does anyone know what this might be? Has anyone seen this before? is it even bad and if so how should i go about gettin rid of it?
sorry no pics but my cameras broken.

 

[5h3rW1N]

it kind of sound like a dying shroom. a already dead shroom, that shows the internal organs. if it is a stringy curling white it would be the inside of the shroom. how old is the shroom rock, or how long have you had it?