This configuration suggests biological origins and had been cited by critics as a key missing element in the meteorite evidence. Such a chain of magnets outside an organism would immediately collapse into a clump due to magnetic forces. On Earth, certain bacteria have evolved to grow chemically pure, defect-free magnetite in chains within their cells, surrounded by a membrane. Under the electron microscope, using a special technique, the team could see fossilized outlines of both the chain and the membrane, Friedmann said. A separate team, building on its extensive earlier work, reports new details concerning the shapes of the crystals.
Shape is another element considered significant in determining whether the origins are biological.
In this case, the team says it discovered that the shape of the crystals formed by the Earth bacteria was different from what scientists had thought for about 15 years. They found that about 25 percent are identical to those found in Earth bacteria. Word of the latest findings piqued the interest of even some outspoken and persistent skeptics. On grounds that the simplest explanation is best, he argues that if 75 percent of the crystals were produced by nonliving processes, most likely they all were. At least one group has come close to reproducing similar crystals with non-biological techniques.