ALH 84001 carbonate mineral globules
The possible evidence of life in ALH 84001 was all found in and around carbonate mineral globules. In this microscopic view (~0.55 mm across), the cores of the globules are orange-brown, fading outward to colorless, and are surrounded by black and clear bands. Other minerals in ALH 84001, which surround the globules, include orthopyroxene and plagioclase. Both are colorless in this view.
Photograph and caption by Allan Treiman, Lunar and Planetary Institute