Looks like xenia, get some peperment shrimp. They will eat it if it should not be there. I have 5 and they are reclusive and fun...maybe because of the 2 cleaners I have. My wife loves them, calls them "ninja" shrimp. They just dart out at feeding time. Got them from advice here on how to control aptasia. Aptasia are gone! (yeah I know I can't spell)