what is this?

[grimreeferfish]

What is this brownishyellowish leather looking pouch growing on my polyp rock? Thanks in advance.

 

[saxman]

It's hard to tell from the photo (I can't see any surface morphology), but if I had to take a guess, I'd say it's a sponge.

 

[grimreeferfish]

Thanks for the reply. Will try for a better pic tonight.