In ancient Jerusalem there was a chronic lack of good silver coins. The only city nearby which produced them was Tyre, a coastal city famous for the purple dye it extracted from within the murex shell. As a hub of commerce, Tyre produced many coins, and a good number found their way to Jerusalem.
The shekel was the common coin of the times and as such was, most likely, the primary silver coin to reach jerusalem, and probably used to pay the Jewish Temple tax. The front shows the head of Melquarth, the semitic equivalent of the hero Hercules, and the back shows an eagle standing – representing the powerful military and commercial fleets owned by the Tyrians. It is the shekel that historians have identified as the coin in which Judas would have been paid (the famous ‘thirty pieces of silver’) for his betrayal of Jesus.