The HMS Challenger, under the command of John Young Buchanan, discovered that the ocean floor was covered with countless manganese nodules of all sizes. It was later discovered that in certain areas (especially in the Pacific Ocean) there were as many as 11 kg per square meter. They grew only 1 mm every thousand years, which in total amounted to 6 million tons each year. In the Pacific alone, it is estimated that there are 1.66 trillion tons. Practically an inexhaustible resource.
