Science deniers do not know or do not want to know that coral is an animal, even though it looks like a plant/flower; they want to remain stupid.
Unlike plants, which are soft, coral is extremely hard from the limestone it secretes.
Once the organism dies, the limestone--which looks and feels like rock--remains to aggravate ships and humans foolish enough to bump into it.
With time, wind and weather and waves work their usual wonders...
to reduce the former home of millions of animals to something resembling stones...
and then sand (with nasty surprises for anyone barefoot)...
to the final result: nice beaches and turquoise waters for tourists.