Bubble algae?

[jgvergo]

I've never seen a ring of small bubbles around a large one like this...

 

[mahindra.dev]

I say its bubble algae.

 

[Tom Blevins]

emerald crabs will work on it.

 

[jgvergo]

emerald crabs will work on it.

I have an emerald crab, but he hides under the rock work most of the time.

 

[Tom Blevins]

I don't know your tank size but I had this guy that mowed through it too.

 

[jgvergo]

I had one for a while. Really loved it too. I had to reboot my tank b/c of a move and I decided I did not want to deal with venom any more