The nodules were discovered during the voyage of the HMS Challenger in 1873. When those sailors brought them to the surface, they would have grasped them in their hands like rocky potatoes, crumbling at the edges. To touch, they might have felt smoother on top, but rough on the underside, like pumice, where they had been growing into the surrounding sedimentary grains. If they’d held them to their nose, they’d have detected no scent.

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