Manganese nodule
= Manganese nodule
{wiki=Manganese_nodule}
Manganese nodules are round, mineral-rich deposits that form on the ocean floor, primarily composed of manganese and iron oxides, along with small amounts of other metals such as nickel, copper, cobalt, and rare earth elements. They typically have a hard, nodular texture and can vary in size from a few millimeters to several centimeters in diameter.