The Neolithic was defined by stone, the Bronze Age by bronze, the Iron Age by iron. Our era can rightfully be called the age of rare-earth metals. They lie at the very heart of the production of microchips, smartphones, electronics, electric vehicles, solar panels and wind turbines. Without them, navigation and defence systems do not work, medicine does not develop, and digital infrastructure is not built. They conceal the invisible backbone of the world to which we aspire.