"Seismic imaging reveals ancient ocean floor surrounding Earth's core"

Seismic imaging has revealed that a massive ocean floor, likely surrounding much of Earth's core, is lodged roughly 2,000 miles below the surface, between the core and the mantle. This thin, dense layer may encompass the entire core-mantle boundary and is made up of underground mountains that allow heat to escape from Earth's molten core. The presence of this layer could buffer heat flow across the core-mantle boundary, which is important because the temperature conditions in this portion of the Earth have been shown to strongly impact the planet's magnetic field.