Can someone help me with an ID?

[NewEnglishMutt]

What is the blackish things growing on the rocks with my corals? The corals don't seem to care that it's there I just don't know what it is

 

[Keithcorals]

Sponge
And it's a cool looking sponge it shouldn't bother anything.

 

[NewEnglishMutt]

Is it another type of coral? Or something I should be concerned about?

 

[NewEnglishMutt]

Ok sweet it's been there as long as I've had the tank I had a feeling it was a sponge or some kind of filter feeder but wasn't sure.