In his Critias dialogue, Plato claimed that the metal was mined in many parts of the continent and that its buildings – including a Temple of Poseidon and royal palace – were coated in it. It is perhaps unsurprising, therefore, that orichalcum has been at the heart of the centuries-old search for the drowned continent. In late 2014, a diver named Francesco Cassarino discovered 40 ingots of a mysterious metal nestled within