This skull from Ancient Rome has a tiny coin glinting out of its mouth: the money is an obal, one of the most notorious grave-goods of the Ancient Mediterranean. The literature of Greeks and Romans commonly asserts that the obal was meant to pay the price for the dead to be carried over the river Styx by Charon, ferryman of the underworld. (In Latin, the obal is frequently referred to as a _viaticum_, meaning “provision for a journey.”) Pagans generally believed the land of the dead was a grim place, occupied by spirits who more resembled spiritual shells of the deceased rather than conscious beings. Improper burial was thought to create restless ghosts. The practice of burying coins with the dead varied — sometimes there were multiple coins, other times there were tokens versus money, and sometimes the coins were not put into the mouths but on other body parts. Regardless, the custom was ubiquitous: the second image is an obal with a Medusa head that came from the Black Sea. It was also a very long-lived tradition, continuing into the Christian era of Late Antiquity. The third image is Charon the ferryman as painted by Michelangelo in the fresco “the Last Judgment” on the Sistine Chapel.
Source(s): See Wikipedia and Ancient Origins for images.