If you think Mount Everest is the tallest mountain on Earth, you’re not alone – but also, you’re not entirely right, because there are peaks inside the planet that are bafflingly large.

Researchers call these huge buried ranges ultra-low velocity zones (ULVZ). They’re located in the core-mantle boundary inside the planet, which sits around 1800 miles deep.

The mountains there can be “4.5 times the height of Everest.” That’s more than 24 miles high, says University of Alabama geologist Samantha Hansen.

“We found evidence for ULVZs kind of everywhere. It’s it’s big enough, we can see it.”

Scientists are able to “see” these peaks using seismic data from earthquakes and atomic explosions.

There’s a lot we don’t know, but scientists theorize they could be the remains of ancient oceanic crusts that were pushed inside the planet, or perhaps pieces of mantle that were superheated by the earth’s core.

They’re not alone down there (in there?) either – there are also large low-shear-velocity provinces or “blobs,” which scientists also believe could offer clues into how tectonic plates shift from the crust into the mantle.

Hansen uses seismology stations in Antarctica, a place far from any blobs or tectonic plate shifts, to study the ULVZs. She believes their existence there supports the theory that they were once part of the planet’s ocean floors.

“Seismic investigations, such as ours, provide the highest resolution imaging of the interior structure of our planet, and we are finding that this structure is vastly more complicated than once thought.”

Researchers may not know exactly what’s going on in there, but if history has taught us anything, it’s that science will find out.

Go science!