Potential patches of Earth's ancient crust, sometimes called "sunken worlds," may have just been discovered deep within the mantle, thanks to a new way of mapping the inside of our planet.

This is a 3D view of the top 1,000 kilometers of the earth's mantle beneath the central Pacific showing the relationship between seismically-slow "plumes" and channels imaged in the study.

Extracting more information from waves So far, the researchers can only speculate. "We think that the anomalies in the lower mantle have a variety of origins," says Schouten. He believes it is ...