Hammer Coral developed bubble.

[Madaga]

Has anyone experienced this before? Everything else seems happy and healthy in my tank. Is this something I should be concerned with? It opens and closes as usual but has that unsightly bubble.

It sits by itself toward the bottom of a 72 gal tank with medium water flow and moderate lighting. Seems happy, just has the bubble

 

[ahvrivera]

This has happened to mine also. In my experience this happens when the conditions are good and it starts to split into more heads. Mine grew one like this and 2 weeks late it had 5 heads in the place of one.