A quarter of the magnetic material in a famous martian meteorite was most likely created by microbes, insist a team of researchers from the United States and Canada. The claim isn’t new, but additional evidence for it is. In the August issue of the journal Applied and Environmental Microbiology, a team of nine researchers headed by Kathie Thomas-Keprta, an astrobiologist at NASA’s Johnson Space Center, presents new evidence that at least some of the magnetite crystals in ALH84001 are organic. About 25 percent of the magnetite crystals in ALH84001 have passed a set of criteria that only biological magnetite crystals have ever met before.