The rate of deterioration, mainly. Years ago I may have lost a large LPS in a similar manner. I don't remember exactly.
I only know of Wheelman's tank based on these pictures, but I see that he has a fairly coarse substrate.
Maybe the coral was rocking back and forth with water movement which irritated the flesh that wrapped under the skeleton. That flesh decayed, bristle worms started eating and wound up eating the coral from the inside out.
Maybe that's why we're seeing holes in the flesh even though it's in a protective cage.
Maybe it's a predatory worm, too.
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Mitch
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