About a million years ago, an asteroid smacked into the normally tranquil surface of Mars. The impact released a fountain of debris, and some of the rocky fragments pierced the sky, escaping the planet’s gravity to journey through the dark.

Some of the rocks eventually found their way to Earth and survived the plunge through our planet’s atmosphere to thud into the surface–including a hefty 15-pound shard that crashed into Morocco in 2011. Now known to scientists as the depleted shergottites, this collection of more than a dozen space rocks makes up an intriguing portion of the 317 known Martian meteorites—the only material from Mars we have on Earth.

Determining what part of Mars these meteorites came from