The pix is not clear enuf, if you could take a macro shoot, mayb more pro bros will comment.
It's a acan right ?
Here my amateur view ......
From the pix, i can see pits, which may mean, the coral is not "opening" or worse case, the flesh is receding. On the right side, maybe clear indication of exposure of the "bones". Hence, i think the coral's healthy is in question.
If you wanna save it from further receding, please it in low flow and right at bottom of tank, maybe away from direct MH.
Just my 2 cents.