Phobos, Mars' biggest moon, may contain traces of ancient life that perished on the Red Planet billions of years ago, preserving it in pure form.

Japan Aerospace Exploration Agency (JAXA) astronomers believe that several asteroid impacts on Mars over time may have moved material off the planet and transported it to its moons.

Phobos, which is just 9,377 kilometers from Mars than the farther away Deimos, is more likely to have picked up debris from its home planet, per NASA.