The earliest depiction of the ouroboros—a serpent coiled in a circle, eating its own tail—was found in the tomb of Tutankhamun, a pharaoh who ruled Egypt around 1320BC. It was used in his funerary texts to depict the infinite nature of time, and later cropped up all over the place. In Ancient Rome it signified the seasonal cycle of the calendar year; in Norse mythology the snake was large enough to encircle the world. The idea is also an allegory for the modern financial system. It depicts how credit risk has been cycled out of banks, only to be gobbled up by them once more.