NASA's Curiosity rover has discovered large organics just below the Martian surface, including carbon-based molecules, some of which have not been seen before on Mars. These molecules, found in a 3.5-billion-year-old clay-rich rock from Gale Crater, include a nitrogen-bearing ring structure that is linked to the chemistry that can precede RNA and DNA. The findings suggest that the building blocks of life may have been present on Mars, although it is unclear if they are related to life on the planet.