So we have been fairly thorough in our discussion about coral reefs, which of course are prominent, oceanic features made of hard limestone skeletons produced by tiny coral animals.

Bleaching occurs when the tiny plant-like coral organisms die, often because of higher temperatures, and leave behind only a white limestone reef skeleton.

Because it was underwater 30 million years ago, the cave is made from limestone composed of fossilized shells, skeletons and coral.