410 miles underground mountains bigger than Everest?

A new study into the boundary between the upper and lower mantle of the Earth have surprisingly found topography potentially 'rougher' than any mountain on Earth. They are located at a boundary 410 miles straight down into the Earth from the planet's surface. Using wave data from an 8.2 magnitude earthquake in Bolivia, these mountains and other topography were discovered which could be even bigger than Everest.