A cartouche is an oval or oblong pendant enclosing hieroglyphics above a single straight line, giving the title or name of an ancient Egyptian ruler. These were often made of gold and placed around the neck of a body being prepared for burial so the deceased person could be identified in the afterlife. They could also be hung from a sarcophagus or coffin.
When Napoleon’s soldier looted the tombs of ancient Egypt in the 19th century, the shape of the pendants found with the bodies reminded them of the oblong shape of their bullets. Because they could not read the hieroglyphics, they did not know what the pendants were for, and called them cartouches, the French word for gun cartridge or bullet