Sense
Magnetoception (or magnetoreception) is the ability to detect the direction one is facing based on the Earth's magnetic field. Directional awareness is most commonly observed in birds, which rely on their magnetic sense to navigate during migration. It has also been observed in insects such as bees. Cattle make use of magnetoception to align themselves in a north-south direction. Magnetotactic bacteria build miniature magnets inside themselves and use them to determine their orientation relative to the Earth's magnetic field.
Magnetix
The leading American expert in the area of the effects of swallowed magnets on the human body is radiologist Dr. Alan Oestreich. As early as 2004 he warned the medical community about the dangers of "multiple magnet ingestion", but the case studies never made it into the popular press. A pediatric gastroenterologist, Dr. Marsha Kay of the Cleveland Clinic, is one of the first to write an article for health consumers on steps to take if a child is suspected of swallowing a magnet.