“The one we have just put on display formed around the tooth of a megalodon, a species of giant shark that became extinct more than 3m years ago. “Typically, a nodule takes shape around an object – like a clam shell – that has fallen onto the seabed,” says marine biologist Adrian Glover of the Natural History Museum, London. Later it was shown they grow by absorbing metal compounds in seawater. Hauled from seabeds more than 4,000 metres deep, they were initially thought to be formed from volcanic rocks and salts.

Polymetallic nodules were first discovered during the 1872-6 expedition of HMS Challenger, whose round-the-world voyage laid the foundations of modern oceanography. Photograph: OAA Office of Ocean Exploration and Research For better or worse, these mineral spheres are going to play a critical role in determining our future – either by extricating us from our current ecological woes or by triggering even more calamitous outcomes.Ī field of manganese nodules in the deep waters next to Hawaii. On one side, proponents of nodule extraction claim it could save the world, while opponents warn it could unleash fresh ecological mayhem. “Mining means destruction and in this case it means the destruction of an ecosystem about which we know pathetically little,” he says. “It is hard to imagine how seabed mines could feasibly operate without devastating species and ecosystems,” says UK marine biologist Helen Scales – a view shared by David Attenborough, who has called for a moratorium on all deep-sea mining plans. At the same time, plumes of sediments, laced with toxic metals, would be sent spiralling upwards to poison marine food-chains. Delicate, long-living denizens of the deep – polychaete worms, sea cucumbers, corals and squid – would be obliterated by dredging.

They say mining deep-sea nodules would be catastrophic for our already stressed, plastic-ridden, overheated oceans.

“We cannot increase land supplies of these metals without having a significant environmental impact. “We desperately need substantial amounts of manganese, nickel, cobalt and copper to build electric cars and power plants,” says Hans Smit, chief executive of Florida’s Oceans Minerals, which has announced plans to mine for nodules. By dredging up nodules from the deep we can slow the scorching of our planet’s ravaged surface. These metallic morsels could therefore help humanity save itself from the ravages of global warming, argue mining companies who say their extraction should be rated an international priority.

Dredge mining pros and cons