Casu marzu is a traditional Sardinian sheep's-milk cheese deliberately ripened past ordinary fermentation into a soft, weeping paste by the larvae of the cheese fly, Piophila casei. Its name means "rotten cheese" in Sardinian; the maggots break the fat down into a pungent, ammoniac, intensely spreadable cream that many islanders prize as a delicacy while food-safety law across the European Union bans its sale.