By Jennifer Marohasy’s Blog – Re-Blogged From WUWT
CORALS are animals, closely related to jelly fish, but they differ in having a limestone skeleton. This is hard-stuff, calcium carbonate, and it can persist in the environment and provide an indication of changes in sea level, and also the growth rates of corals, over thousands of years.
Porites corals are typically used to estimate growth rates the Great Barrier Reef. I photographed the surface of this coral when I visited Bramston Reef with Peter Ridd in August 2019. It was so soft, like a carpet, but firm from the corallite: the limestone skeleton supporting individual coral polyps.