Please help I.D this.

[jerrym21]

I have had this thing living on my rock for a few months. I never moves and does not seem to be getting any larger. It's a whitish ball that has craters/holes in it. Long string like "legs" that attach it to the rock. It has no change at all in full light or darkness. I'm just curious.

Any Ideas?

 

[greenbean36191]

It's a sponge with satellites.

 

[jerrym21]

Thanks. I guess I should just leave it alone?

 

[joeychitwood]

They are harmless filter feeders and contribute to cleaner water in the tank.

 

[Frick-n-Frags]

also a good sign of good water.

leave it unless it grosses you out or something more subjective like that

 

[jerrym21]

Do they get bigger or is that the full size? Right now it's about 1/2" dia.
As far as a sign of good water quality. . .I think my water is barely acceptable. All parameters are decent with the exception of nitrates. They run in the 20-30 range and have never been below 10. but I guess its good enough for what I have in the tank cause it's all living after 2-1/2 yrs.