Looks like something might be living in that hole in the center of the acan...might want to check it out and see what's in there. It seems something killed the polyps around that area.
Of course, you can always cut around that area and you might even have a few frags to send to some of us![]()
It's nice you should search for "Rescue Corals" in this site there's another member that enjoys nursing near death corals he has before and after pics. He could probs give you some great advice.