Pigeons have magnets.
Research on pigeon homing suggests that magnetic field information is used for orientation. The ability of pigeons to sense magnetic fields may be associated with a small, unilateral structure between the brain and the skull which contains magnetic in what appears to be single domains.
D000818:Animals; D001921:Brain / Q000502:physiology; D010856:Columbidae / Q000502:physiology*; D006257:Head / Q000502:physiology; D008280:Magnetics; D009949:Orientation / Q000502:physiology*