The Tissint meteorite, which fell in 2011, is the Museum's largest Martian meteorite. This piece weighs 1.1 kilogrammes.
Scientists know it came from Mars because it contains tiny bubbles of gas that have the same chemical makeup as the planet's atmosphere.
By looking at the meteorite's exposure to cosmic rays, we can also tell it was ejected from Mars's surface approximately 700,000 years ago.
Martian meteorites are absolutely critical to our study of Mars because they are the only physical samples of the planet we have on Earth. While many missions have landed on the surface of Mars, allowing us to study the planet remotely, these meteorites permit much more detailed and accurate analyses of the planet's composition.