It was stuck. Or at the very least my brushing across it didn't hurt it at all. When I pulled the wood out and left it in the kitchen sink, it got a whole bunch of white mold on it. I think I shall just discard that piece.
It sort of looked like a the texture on a brain and it springy when you pressed on it, just like wool. It was completely repulsive looking and smelled just awful. I heartily hope I never, ever see anything like that again. :P