Manganese nodules. Photograph of the floor of the Atlantic Ocean, Southeastern United States, showing a large field of manganese nodules. Manganese nodules form when manganese and iron minerals are deposited on the surface of an object such as a tiny piece of bone. The minerals in the sea water deposit over a long time; a nodule grows by 1 centimetre in diameter in about 1 million years. This photo was taken by a remotely operated camera during Dive 07 of the 2019 Southeastern U.S. Deep-sea Exploration.