Very nicely preserved and very characteristic Greek drachma from Istros.
David Sear, in his study Greek Coins and Their Values, wrote about this obverse: "The type of obverse has been variously interpreted as representing Dioscuri, the rising and setting sun, and the two branches of the Danube."
Greece
Moesia, Istros, Drachm 340-313 BC
Obverse: facing male heads, the right inverted
Reverse: Sea eagle left on dolphin, Θ beneath eagle's tail, Σ beneath dolphin
IΣTΡIH
Diameter 17 mm, weight 5.72 g
Istros was probably the first Greek colony on the Black Sea to be established between 657-656 BC or between 630 and 620 BC by settlers from Milesia in a strategic position near the Danube Delta. The first emission of money consisted of cast arrowheads, later marked with a circle or with the inscription ΙΣΤ. The coins proper were minted from the 5th century BC. At the same time, Istros was minting silver fractions, and after the suspension of silver emissions in the Lysimachos era, the city began to beat golden staters. The city also minted autonomous bronze coins and coins of the Roman province.