ID need w/ Pics

[Miasma_F]

Anyone have any idea what this thing is? I've pulled it off once or twice before and it has come back, always in the same place. It has taken it about 2 months to get this big (about the size of a large gumball).

Good? Bad? Indifferent?

Thanks in advance,
Matt

 

[fraggin]

looks like a clump of cyno
if it keeps coming back i think i'd get tired of it and cut it off with a chisel

 

[Miasma_F]

Thank you kindly. I kind of suspected as much because I'm battling some cyano in my sand. I think it might be time to change my RO filter.

 

[graveyardworm]

If thats cyano its got to be one of the oddest growth forms i've ever seen. Actually it looks like a hairy monkey nut, but I dont think those grow in reefs. So i'm going to bet that its some kind of sponge.