Help identifying please!

[stlblufan]

Does anyone know what this round thing is? It has feather-like things coming out of the top during the day. Looking down from the top, there is a hole in the center of it (can't get a picture from that angle). I didn't put it in the tank, and it has been growing pretty quickly. Seems to have some buddies, too. I thought it was a sponge but now...not so sure. Thanks for your help and sorry for the terrible pics (also that they're orientation is sideways, not sure how to fix that on here?).

 

[ReeferGirl]

looks like a pineapple sponge - harmless

 

[Domboski]

You need to get a better, more clear pic to be 100% sure. Your description of a center hole makes me doubt its a sponge but its possible.

 

[guarda]

+1 better pic but if you're talking about the green, they're tube worms and harmless. If red, looks like a sponge as mentioned above. I had a few yellow and orange ones. If you're bothered by them or they grow fast, let me know and I'll pick them up seeing as you are in Manhattan too. My linckia loves them.

 

[Josh]

Its a tube worm.