Birds make epic journeys across the globe every year guided by Earth’s magnetic field. But how they detect this magnetic field has left scientists baffled for decades. Now, the the Keays lab at the Research Institute of Molecular Pathology in Vienna might have some answers. It turns out birds of all shapes and sizes have tiny iron balls in their cells found around their ears. And it is these iron balls that are responsible for detecting sound and gravity. Needless to say, these iron balls are not found in humans.