What is this??

[byerlyjb]

Can anyone tell what the green on the Rock is? It doesn't seem like it will come off easy. Curious if anyone knew what it was and/if it was good for the tank. It doesn't seem like it is getting worse.

 

[KJ]

Sponge?

 

[dbl]

Sponge?

Would have been my guess also.

 

[cloak]

Being that it doesn't come off the rocks with ease, I think it's just a prelude to the purple Coralline algae we all love so bad. GL.

 

[gacolt]

sponge.It's good for the tank helps keep nutrient in check.