Stony corals are animals which help build our coral reefs. Most of them live in colonies and secrete a hard skeleton made of calcium carbonate which may have razor-sharp edges. The animals called polyps, form the outer living layer of the coral skeleton. Each polyp sits in a cup-like depression called a calyx . The color in living coral is due to the presence of algae, called zooxanthellae , which live inside the coral polyps.
Corals also have stinging cells which can cause irritation to sensitive skin.
Pieces of coral can lodge in a cut making it slow to heal and prone to bacterial infection. Contrary to a popular misconception, the coral will not grow in the cut. Tiny pieces of coral embedded in the cut and the bacteria associated with them can often produce inflammation and tenderness. Allergic reactions can also occur. Clean the cut immediately and thoroughly using soap and water and hydrogen peroxide to remove the coral debris.