An international team of researchers working with a Martian meteorite found in Antarctica discovered magnetite crystals arranged in long chains within the potato- sized space rock. Those chains could only have been formed by once-living organisms, the U.S. space agency said in a statement. Such a chain of magnets outside an organism would immediately collapse into a clump due to magnetic forces. Each magnetite crystal in the chain is a microscopic magnet, and they are strung together like pearls in a necklace, according to the researchers.
Magnetite is an iron oxide, something like iron rust.
The meteorite under study, known to scientists as ALH84001, was discovered in the Antarctic in 1984 but caused a furore in 1996 when NASA researchers first raised the possibility that the rock might contain evidence of ancient microbial life. Since then, the rock's significance has been disputed by astrobiologists around the world. The current findings, reported in Tuesday's editions of the Proceedings of the National Academy of Sciences, appear certain to feed the controversy. Friedmann's research team said the magnetite crystals formed inside organic material whose structure held the crystals together. The bacteria decayed but the crystals remained, the researchers reported.