It's mojano. Get rid of it. We thought they looked nice and left them alone. We now have hundreds of them. They have a very powerful sting and will kill any coral it comes in contact with. Racoon butterflyfish will eat them, but they may also pick on feather duster's, other anenomes like BTA's, and zooanthids.
I must respectivly disagree,
that in no way looks lile Palythoa. Paylotha grows in mats, that appears to be an independent polyp.
That is similar to a Manjo but a bit different. I've seen them in my tanks, Kill it!!!! make strong kalk paste and inject it with a saringe (1-5ml). When it loooks stressed peel it off the rock carefully with tweezers or heomstats.