The “Largest Piece of Mars on Earth” just sold at auction for about $5.3 million— $5,296,000, to be exact. The chunk of the Red Planet then travelled 140 million miles to Earth, crashing in the Sahara desert. The sample’s chemical make up was compared with Martian meteorites that were discovered in 1967, when the Viking space probe landed on Mars. This type of Martian rock was formed by the slow cooling of magma on Mars. The auction house estimates that there are only 400 Martian meteorites out of the more than 77,000 officially recognized meteorites that have been discovered on Earth.