Caption

Sample of Martian meteorite ALH 84001. This meteorite was found in Antarctica in 1984. In 1996, NASA researcher David McKay announced the discovery of tiny tube-like structures within the rock, thought to be fossils of microscopic organisms (microfossils). The fossils are billions of years old, and the first evidence for extraterrestrial life. The rock was ejected from Mars by a huge meteorite impact about 16 million years ago, and fell to Earth about 16,000 years ago. Photographed at NASA's Johnson Space Center, in the USA.