I have some pulsating xenia, so that is a possibility, but it's not the right color. I have some tiny sprouts of those and the polyps are much larger.
It does look goniopora-ish Frankie, the thing that really confuses me is the rock it is sprouting on was air dried outside for about week and then "cooked". I've never had any goniopora and the tank the rock came from didn't have any either. Although, anything is possible...
I do have some acros and the polyps are about the same size, but I have no idea how it would have gotten there, it's about 5-6 inches away from the nearest one vertically. Is there any way one of my acros could have released some polyps for reproduction?