In 1911, near the Egyptian village of El Nakhla El Baharia was recovered a meteorite of martian origin. It belongs to a class of martian meteorites (called "nakhlites") that are derived from a ~1.3 billion year old sill or lava flow. They are mainly composed of magnesium, silica and iron. The Nakhla meteorite showed traces of a very particular form of silica, hydrated and amorphous: opal. This opal was the first in a few traces of martian opal. However, the hydrated silica in the Nakhla meteorite showed showed something rather special: it was very similar to the sort of opal that, on Earth, forms around hydrothermal vents. Around these vents, microbial life thrives and prospers. Could this suggest opalised microbial fossils on Mars? Are we this close to finding fossil life elsewhere in the universe? Further research will tell...