ID of stuff on a new mushroom

[Kissfan79]

Hey guys......can anyone tell me what this grey stuff is on the new mushroom frag I just picked up? You can see the green mushrooms but there is some grey "stuff" on the rock. It is a tad blurry but it looks like cured epoxy or JB weld. The texture of it, though is like the mushrooms...it is sort of soft and has a slightly slimy touch to it. Any ideas?

Thanks, Jim

http://i101.photobucket.com/albums/m52/kissfan79/DSC01633.jpg

[silvers]

sponge

[Kissfan79]

Is this a good thing to keep on the rock or beneficial in any way or should I remove it? Do you think it will change in color or stay grey?

Thanks!

Jim

[drummereef]

I'd leave it be. Harmless filter feeder. ;)