Regular growth rings laid down as the skeleton thickens can be used to estimate the age of the colony. Sexual reproduction involves the production of eggs and sperm to create young that can disperse and settle new areas. The larval stage, called a planula, can drift with currents until a suitable surface is found. Once the larva settles, it metamorphoses into a polyp form and secretes skeletal material that attaches it to the seafloor. Then it begins budding, creating more polyps that will form a young colony.
Asexual reproduction can also occur naturally by fragmentation of branch ends.
Reproductive maturity may be reached after 10 to 12 years and reproduction may occur annually. Some species may live even longer. On Hawaii's deep reef slopes and throughout the world, black corals host unique communities of marine life. Their tree-like colonies create habitat for crustaceans, bivalves, and fish. Each coral may host a different combination of species.