Rachel Nuwer, reporting for the New York Times:
The substance, called plastiglomerate, is a fusion of natural and manufactured materials. Melted plastic binds together sand, shells, pebbles, basalt, coral and wood, or seeps into the cavities of larger rocks to form a rock-plastic hybrid. The resulting materials, researchers report in the journal GSA Today, will probably be long-lived and could even become permanent markers in the planet’s geologic record.