Oooh! There we go! There we go! Finally!
So this looks like it is probably Evoplosoma.
Most, almost every time that you see a sea star feeding on a coral like this it is probably Hyposteria or Evoplosoma.
There's certainly two or three other genera which are predators on coral, but these are the most numerous ones.
They're very efficient and we've seen them devour the polyps inside primnoids even, kind of like the way I just had my cookie.
Anyway...
But, looks like it's done quite an efficient job of cleaning off the animal from the bottom all the way to the top.
It makes me wonder how old it is, because it's probably been around for quite a long time
and for all I know it's spent the last year or so just devouring it's way up to the top of this animal.
Hard to say, but there's other evidence that certain sea stars spend a year or longer just hanging out on a coral, eating its way through it.