Marine explorers have discovered a "pristine" 3km (2-mile) coral reef at depths of 30m (100ft) off the coast of Tahiti, French Polynesia. It is one of the largest discovered at that depth ...

Beneath the soft bodies of scleractinian, or stony corals, polyps secrete a calcium carbonate skeleton, and it is this skeleton that becomes the foundation of coral reef ecosystems. Coral colonies ...