Little is known about sexual reproduction in these corals. Sexual reproduction occurs after the coral colony is established. A colony will produce eggs and sperm, which meet in the water to create larvae that use currents to disperse and settle in new areas. The larval stage of the coral, called a planula, will drift along until it finds a surface on which it can grow. Once it settles, it metamorphoses into its polyp form and creates skeletal material to attach itself to the seafloor. It will then begin to bud, which will create new polyps and eventually form a colony. In areas with ideal conditions, black coral colonies can grow to be extremely dense, creating beds. In some black corals that have been closely examined, colonies will grow roughly every year. Sexual reproduction occurs after 10 to 12 years of growth; the colony will then reproduce annually for the rest of its life. The male to female polyp ratio is 1:1, with females producing anywhere from 1.2 million to 16.9 million oocytes. A large tall coral tree is somewhere between 30 and 40 years old.