About 300 miles (480 kilometers) southeast of Tokyo, a crewed submersible peered at a ledge of volcanic rock and spotted something unusual. A limpet with a thin, bluish shell sat on the rock at a depth of about 19,430 feet (6 kilometers).
The…

About 300 miles (480 kilometers) southeast of Tokyo, a crewed submersible peered at a ledge of volcanic rock and spotted something unusual. A limpet with a thin, bluish shell sat on the rock at a depth of about 19,430 feet (6 kilometers).
The…