Many scientists believe that the Moon formed when a Mars-sized planet, called Theia, struck Earth around 4.5 billion years ago.
Learn more about the large blobs of material in Earth's mantle which could be remnants of protoplanet Theia at:
Now, a team of scientists theorize that Theia’s remains are what formed two mysterious, continent-sized blobs of rock buried deep in Earth’s mantle.
For decades, seismologists have puzzled over these two blobs, which sit below West Africa and the Pacific Ocean, and straddle Earth’s core like a pair of headphones.
Up to 1000 kilometers tall and several times that wide, “they are the largest thing in Earth’s mantle,” says Qian Yuan, a Ph.D. student in geodynamics at Arizona State University.
Seismic waves from earthquakes abruptly slow down when they pass through the layers, which suggests they are denser and chemically different from the surrounding mantle rock.
These blobs might simply have crystallized out of the depths of Earth’s primordial magma ocean. But based on new isotopic evidence and modeling, Yuan believes the blobs are the guts of the theoretical alien impactor planet.
The study is currently under review.
https://phys.org/news/2021-03-theory-large-blobs-material-earth.html
https://www.sciencemag.org/news/2021/03/remains-impact-created-moon-may-lie-deep-within-earth
https://www.sciencealert.com/vast-mysterious-fragments-of-an-alien-world-may-be-buried-within-earth-study-finds