The Magnetic Sense Is More Complex than Iron Bits

Many unrelated animals, from bacteria to birds, have tiny particles of magnetite in their bodies. For many years, biologists assumed that these magnetized bits of iron were the key to understanding the geomagnetic sense in migrating organisms: cells sense the torque of these iron crystals when they align north, like tiny compass needles. This theory, however, might be only part of the story. The real key may rely on proteins that respond with intrinsic iron atoms of their own. At least, that...