what is this worm? Parasite?

[noirsphynx]

I agree, those aren't worms. I've had that happen in my tank if the mushroom gets torn or if it's on it's way out. It was great in my tank. Here's a pic of it on May 29 not long before you took it home.

[blacknife]

One of mine did that when i was chipping it off the rock it was on. I read on RC what they were called. i just left them in peace in a nice place and they cleared up over a few days.