Plate coral problem.

[Delphinus]

Sorry to hear it.

I suggest you might want to try establishing a cause for the tissue recession. I find LPS can be intolerant of certain things like any kind of ammonia or nitrite spike, or excessive nitrate buildup, and can start to slough off tissue in short order. So if you haven't already, check everything you can think to check (ammonia/nitrite/nitrate and perhaps pH, phosphate as well if you can test for those) and see if you can pinpoint a cause. Too late to save this coral, but hopefully if there's something sinister afoot, you can catch it before something else happens.

Maybe nothing wrong, but it's something I'd do if I lost a coral like that.

Good luck.