That's exactly the way plate corals die. They do fine in fact look great for about 12 months then go on the rapid decline you're seeing. The Gionapora is not recommended

"Plate" coral seems to be dying

Robert could you possibly tell me what is happening to plate coral, i have had it for about a year and i noticed its current condition yesterday. i hope it is going through a stage and not dying

Well... I looks like its dying. That's exactly the way plate corals die. They do fine in fact look great for about 12 months then go on the rapid decline you're seeing. The Gionapora is not recommended for this reason although hobbyists cant refuse them because they look so good. Sorry

We are very sad about the plate coral, it kind of was the center piece of the tank. if I would have known that it only lasts less than a year I would never have purchased it. do you have a good coral book you could recommend, something to help with the kind of corals that are good to keep and help me not to make this mistake again. thanks

Hummm this morning it dawned on me that I gave you the wrong information... I really don't know what I was thinking but somehow I related your plate coral to a Gionapora aka flowerpot.

The plate isn't as fragile as the flowerpot and some will argue that they are relatively hardy. I've lost a few in my days, most around one year. From my experience if a coral will live in your tank longer than a year its definitely well acclimated.

Also a helpful tip is - not all species have the same tolerance or arrive in your tank in the same health condition. Your plate was gigantic! A couple of possibilities

It was "stung" attacked by another coral (observe this "Stinging" with a flashlight when the lights are out)
Was lacking lighting
Was in poor health (not likely)

As far as books the most comprehensive (yet sometimes cryptic) is TRA by sprung A must have is a practical guide to corals by Putterbaugh and Borneman

Hope some of this helps
Robert