That looks like Anthelia to me.Which is one of the harder to keep corals.Its actually in the same family as xenia,just no where near as hardy.
My first coral was a blue anthelia like yours.The entire colony crashed when I used chemi-clean for a case of cyano.
i got new lights, i have a t5 fixture now, 156W... but this really sucks, i dont want to kill this coral, i moved him up higher and in better flow, hopefully he'll come back around