what I found was that is is more closely related to a stony coral than an anemone and that it does kill most corals and apparently also kills anemones in competition. I would look at removing them from my tank. oh and they also seem to coat the bottoms of things and eat brine shrimp.
If they aren't in a bad spot, I'd enjoy them for the time being. They look a little like Orange Ball Anemones.