Do your spikes look like small hardened tubes, about 1/8 inch long? I have these taking over, if disturbed they throw out a thin webbing. I believe the coraline has covered them and gives them the appearence of being purple. With that said, touch them--if it feels like a sponge (literally) then its most likely one, if hard then I would say no. With sponges, or at least the HH I have there is always an opening present (sometimes more than 1).