A closer look
Imagine eating so much metal that you permanently turn your body into a navigational instrument. These brilliant little microbes figured out that aimlessly swimming around is a waste of energy. Instead, they biomineralize iron from their environment to grow a chain of magnetic crystals right down their center. This biological hardware forces them to passively align with the Earth's geomagnetic field lines. Because magnetic field lines tilt downward toward the Earth's surface, the bacteria effortlessly ride the magnetic slide straight down into the murky, oxygen-deprived sediments where they thrive.
