This cartoon shows a subducting oceanic plate traveling like a conveyor belt from the surface down to the lower mantle. The white arrows show the comparatively well-established shallow recycling pathway in the top layer of the plate (crust and sediments), that feeds into arc volcanoes. The research team's new findings from studying diamonds reveal a deeper recycling pathway, shown in light blue. Water infiltrating fractures in the seafloor hydrates the rocks in the interior of the plate, forming "serpentinite", and these hydrated rocks can sometimes be carried down to the top of the lower mantle. This is a major pathway that transfers water, carbon, and other surficial elements deep down into the mantle.