What is this?

[idgy]

This was on my live rock when I recieved it and seems to be 'kind of' growing.

Does anybody know what this is?

Thx!

 

[wrightme43]

Are you sure its growing? It looks like a dead coral to me. I could of course be wrong for the first time in the last two minutes. LOL Steve

 

[ribbetribbet]

my best guess would be that maybe their was a stone coral growing on it and it died leaving that patten on the rock. has it grow since you got it.