Question: how many types of coral are there?

Pete Gwynne answered on 15 Nov 2017:

there’s about 2500 individual species, but they are quite often grouped as either hard corals (that make a kind of skeleton for themselves) or soft corals. coral reefs might be home to 2 million species though! there’s a really great program on the BBC at the moment called Blue Planet which is all about this sort of thing.