Great article with lots of photos, including of Belize....

Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Coral reefs are mostly underwater, which in rare cases grow out of the water, structures made from calcium carbonate secreted by corals. Coral reefs cover less than one per cent of the world’s oceans but support incredible biodiversity. Check out some of the unique structures made from calcium carbonate secreted by corals.

http://tiger6300.blogspot.com/2013/03/most-impressive-coral-reefs.html