Is thís some kind of sponge?

[jeffchapok]

I have 8 or so of these black things on my rocks, anywhere from aspirin to dime sized. Most of them are underneath ledges in the dark. This is the largest one. I think it may be some kind of encrusting sponge, but I'm not certain.

Does anyone recognize what it is?

 

[Reef of L]

Yes, I believe it a black sponge. I get a pink version it from time to time. The only luck I have had is to pull the rock and scrub it off, if possible. Hope this helps

 

[WV Reefer]

I have 8 or so of these black things on my rocks, anywhere from aspirin to dime sized. Most of them are underneath ledges in the dark. This is the largest one. I think it may be some kind of encrusting sponge, but I'm not certain.

Does anyone recognize what it is?

^ yep. It’s a sponge. Most are not a problem but some types can grow rather aggressively.

 

[jeffchapok]

Thanks guys. They aren't a problem at the moment, so I think I'll leave them alone and see what happens.