Bacterial magnetite crystals are exceedingly difficult to study, being on the order of 100 nanometers long, or 100-billionths of a meter, and of complex shape.

They want to use their precision techniques on samples from the meteorite as well as on magnetite crystals produced inorganically.

The Nasa study, led by Kathie Thomas-Keprta, found carbonate discs and tiny magnetite crystals inside the space rock.

A chain configuration, they point out, is one of the most distinguishing characteristics of biologically produced magnetite crystals.

The nucleation and growth of the magnetite crystal.

The 38-year-old geobiologist said he believed that magnetite crystals enabled animals from bees to whales to navigate by using the earth's magnetic field.

After a week, magnetite crystals stuck to the glass.

Most regions of the brain had five million magnetite crystals per gram of tissue.

It is tempting to invoke magnetite crystals to explain many other mysteries of the human brain, Dr. Kirschvink said.