Strange blobs in Earth’s mantle are relics of a massive collision

Two mysterious blobs of rock in Earth’s mantle could be remnants of the planetary smash-up that formed the Moon. The formations sit in the layer between the crust and the core, are thousands of kilometres long and are slightly denser than their surroundings. Computer simulations suggest that they are from the protoplanet Theia, which smashed into Earth 4.5 billion years ago. Some of Theia’s remnants were flung into orbit, where they coalesced into the Moon.