growth on zoa frag

[Bdeppen]

I have had this frag rock of zoas for a few months now. You'll noticed a black bubble like growth in the center of the eagle eyes. This was on the frag when I got it. Since then it has multiplied and spread to nearby pieces of live rock. You'll notice it now on top of the frag rock and to the right of the hermit's shell actually growing on my live rock now. Just wondering if this is normal or is it something I should be trying to remove from my tank? Thanks for the help!

 

[unit15]

Sponge?

 

[kichimark]

Yeah that is a sponge. I have the same type on a rock in the side of my tank but the only inhabitants on that rock is a colored feather duster. From my experience though, zoas will not grow on top of them and they are easy to remove. Did you still want to leave it? If not just use your fingers or something else to peel it off.