I have a new spunge I think

[garydm]

anyone care to take a stab on this one

its been growing slowly on the back of my rock
Thanks in advance and should I keep it or kill it:question:

 

[Bifferwine]

It is just a yellow sponge. It's harmless.

 

[Smitty]

+1 Biff

 

[garydm]

good cause its in a bad spot....thanks ill keep on truckn

 

[Piratefish]

I found three white ones in my tank. They seem harmless but they also seem to be growing fast!