[aerohead]

Originally Posted by freebeard

I picked only one paper to scan, so this is cherry-picking, but:

The evolution of modern corals and their early history


en.wikipedia.org/wiki/Global_temperature_record

It appears that coral revert to a soft-bodied form at times, and the reef is actually built by algae in the coral's epidermis.

Apparently... from a 10 minute investigation...

(the term aragonitic biomineralization reminds me of an old inactive forum member)

The coral provides the calcium carbonate scaffold on which the algae populate.
The algae give coral its color.
During a bleaching event, the algae are expelled, and we have only 'limestone' to look at.
If a second bleaching event arrives before the coral can recover from the former ( which is now being observed ), it's likely that the coral will be lost, and 25% of the marine 'food chain' which depends upon it, lost along with it.