NYT

For decades, entrepreneurs have tried to strike it rich by gathering up ugly potato-size rocks that carpet the global seabed. Known as manganese nodules, the rocks are plentiful in nickel, copper and cobalt, as well as manganese and other elements, but lie miles down in inky darkness. Building giant machines to vacuum them up, despite much study and investment, has never proved to be economic.

Now, the frustrated visionaries are talking excitedly about the possibility of belated success, and perhaps even profits.