You probably have a handful of magnets on your fridge at home, but they're nothing like these guys. Neodymium magnets are known as rare earth magnets, and are made from an alloy of neodymium, boron, and iron. They are currently the strongest magnets available. They are so absurdly strong, it's said to be impossible to remove a small disc-shaped neodymium magnet from a refrigerator by hand. These magnets even shatter themselves if they come together with enough force. Today, they're used in a wide range of technology, from MRI machines to speakers and cell phones. Note: NOT on fridge doors.