As Brak said, this wouldn't be possible without the final result being some creature other than coral. Corals--hexacorals, specifically--are colonial organisms with rigid carbonate substrates. In the ocean, there's plenty of carbonate for use, and it has the added benefit of anchoring the colony in shallow water. On land, there's no easily available carbonate, so no substrate; in any event, the rocky skeletons would be even more vulnerable to erosion and collapse on land. No floating plankton, either, and making it wholly photosynthetic and removing the carbonate skeleton would leave us with...well...some kind of algae.

I hate to say it's impossible, because evolution is more inventive than we are, but I don't think it's likely.

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"Call me old-fashioned, but I think fire is magic. And it scares me a lot."

--The State