White fuzzy growth on coral

[Enigma]

Looks like you've stumped 58 people!

I don't know either.

Considering the coral looks like a writeoff . . . if it were me I'd try a hydrogen peroxide dip (1:10 H202:Saltwater) for ten minutes. But (a word of warning) I've have only had that be successful on green algae. It hasn't worked (for me) on red turf algae, or on cyano bacteria, or dinoflagellates.

I have dipped SPS in H202 in the past, and I haven't lost anything as a result of the dips. The SPS have browned quite badly, but have come back quickly. One birdsnest (which was in dreadful shape) has rebounded amazingly.