Almost two miles below the surface of the Pacific Ocean, on a lonely outcrop of bare rock 100 miles from Costa Rica, researchers on a geological expedition found something odd. As their remotely controlled submersible sunk through the black waters toward the seafloor, they saw a collection of purple lumps dotting the rocky bottom.

As they got closer, they resolved themselves into something resembling a bowling ball with suckers. It was a group of female octopuses, of the genus Muusoctopus