What the heck are these things in my tank?

[Anonymous]

I have some things growing on my live rock that I haven't see discussed before. They are small white/ yellowish-white balls growing on my live rock. There are a few dozen and they vary in size from a millimeter to just under an inch. They resemble small cotton balls. I tried to take one off the rock and it released a small hazy cloud into the tank.

Any information would be greatly appreciated.

 

[imow]

Ill bet my underwear they are some sort of sponge or tunicate.

Good filter feeders.

 

[_range_]

I think that means stop exploding the little buggers.