Red coral

Photo: Sylvain Le Bris · CC BY-NC

Corallium rubrum is one of the most coveted and imperilled organisms in the Mediterranean, harvested for jewellery for centuries. The Tremiti marine reserve has allowed colonies on the Cretaccio wall to grow to unusual size — some branches exceeding 20 cm — at depths between 25 and 40 metres. It grows at less than a millimetre per year, meaning each visible colony represents decades of undisturbed growth. The colonies serve as habitat for a range of commensal invertebrates.