Allan Hills 84001 exhibits a black fusion crust covering the gray, orthopyroxene-rich interior. This 174-gram meteorite is 4.5 billion years old and was collected in Antarctica in 1984. It provides a sample of the earliest crustal rocks on Mars. Tiny carbonate globules formed from fluids about 4 billion years ago. In 1996, NASA scientists suggested that these carbonates may contain fossilized evidence of microbes. Although widely debated since, this study has sparked renewed interest in the origin of life and exploration of Mars.