I've seen the green stars and this one has small white flower or star like polyps. I can't find anything like it on line.
I don't know how long it's been in the tank. I bought the entire setup used. I think he said he'd had it about a year, but I don't know if that means the coral too or not. It was attached to the rock on the left but the aptisia you see next to it caused it to detach. The peppermints have taken care of those.