The world's most patient mom may be a deep-sea octopus that tends her eggs for nearly 4.5 years. But now, there may be a new contender for her throne. Scientists have caught a rare glimpse of another deep-sea dweller that may also spend four or more years nursing its eggs, and it does it in an even more unusual place: on hydrothermal vents, where hot water spews from the ocean floor. It's called the Pacific white skate (Bathyraja spinosissima), a bone-white, bug-eyed relative of sharks that can live almost two miles (2,900 meters) underwater. Deep-sea skates, which are shark relatives that resemble rays, lay large eggs that can take years to hatch in cold water.

For decades, futurists have predicted that commercial miners would one day tap the unimaginable mineral wealth of the world's ocean floor. Soon, that subsea gold rush could finally begin: The world's first deep-sea mining robots are poised to rip into rich deposits of copper, gold, and silver 1,600 meters down at the bottom of the Bismarck Sea, near Papua New Guinea. The massive machines, which are to be tested sometime in 2016, are part of a high-stakes gamble for the Toronto-based mining company Nautilus Minerals. Nautilus's machines have been ready to go since 2012, when a dispute between the firm and the Papua New Guinean government stalled the project. What broke the impasse was the company's offer, in 2014, to provide Papua New Guinea with certain intellectual property from the mining project.