White Fuzz growing on Zoa Rock

[nickborowitz]

I have this white stringy fuzz growing on the rocks where I have my zoas growing. I tried to search but for some reason this damn thing only shows white screen when i do.
I tried taking a pic but i can't get one for you guys, does anyone have any ideas as to what it could be? kinda looks like roots only fuzzy.

 

[joebob7]

does it have a sponge base, and then have long white strings?
i think my lfs had some on their rocks, they said it was a harmless sponge though