I think it looks like a Goniopora. If so they are hard to keep for any length of time without a refugium. They feed on plankton and do best when fed each day.
My immediate response is Galaxea.... I know what you mean Colin the polyps look like little 'flower pots' just like Goniopora. What makes it more like Galaxea is the stems are short and out of proportion with the head of the polyp and it seems too fleshy. That is not to say that I am right and your wrong I was just justifying my thoughts and mental processes. I am, however, now very interested as to what it actually is .