Although Mercury's scorching surface is not conducive to life as we know it, an alienhunter believes it could be home to an entire city of extraterrestrials. According to prominent ufologist Scott C Waring, NASA's Mariner 10 spacecraft photographed a bizarre anomaly in the Tolstoj quadrangle region of the planet in 1974. Sharing the discovery on his blog ET Data Base, Mr Waring dubbed it "100 percent proof of life".