The animal is dying. Receding flesh on a plate coral can be difficult to reverse. Your best bet is to offer the animal a stable environment and hope for it to turn around. Small particle food feedings may also help aid the poor fella.
hi is that on a rock? would recommend placing on bottom if not already,moderate flow try to keep skeleton clean,(turkey baster) best wishes,happy reefing
Do you have a bare bottom tank set up by chance? That really helped mine turn around after it started declining. The sand was irritating mine to death that my fish kept dropping on it. The sand was also preventing it from healing. I don’t have a recent pic but it’s been in my bare bottom tank almost a month and it’s completely healed.