Obol

Abdera, on the Thracian coast, was refounded around 545 BC by refugees fleeing the Persian advance into Ionia — a city with displacement written into its founding. By the mid-fifth century it had become wealthy enough from Aegean trade that even its smallest fractional silver was carefully struck. The obol sat at the bottom of that denominational structure, a working coin.

May's die study identifies this type within a tightly sequenced series, useful for pinning down the issuing magistrate's tenure with more precision than the broad date range suggests.