what is this

[photokid]

i am setting up my first reef tank, and i am letting my tank mature a bit before i start adding anything to it. i was looking at my live rock this morning and saw this stuff growing on a few of my rocks. i was just woundering what it is.

 

[george]

Could be some kind of sponge or a worm. The pic is a bit washed out.

 

[photokid]

doing more research i think your right on with it being a sponge

 

[vettesarebest]

Id say its a sponge but nothing to be worried about. Like George said it is hard to tell.