Blobs as planetary fossils

The low‑shear velocity provinces (LLSVPs) beneath Africa and the Pacific might be ancient, compositionally distinct masses that preserve material and events from Earth's early history — either oxidized, grain‑coarse residues of long‑buried subduction or trapped debris from the giant impact that formed the Moon. Distinguishing between these origins (and their ages and chemistry) would change how we model mantle convection, core–mantle exchange, and the giant‑impact era. — If confirmed, these deep‑mantle ‘fossils’ would revise narratives about planet formation and motivate new investments in global seismic networks and laboratory mineral physics.