Sarcoy is the nearest city-state to the Castle and Sarcoy makes three kinds of minted coins:
The gold coin is known as the gold crescent because on the tail aspect there is a crescent moon. The head aspect shows the profile of the monarch in whose reign the coin was minted.
The silver coin is known as a silver spanner, just like the silver coins of several other nearby kingdoms. It portrays the profile of the monarch on the head aspect and a songbird on the tail aspect.
The copper coins are simply called copper pieces, or coppers for short. They depict a fish on both sides.
The above is for flavor only and to explain the naming used in the dungeon. Feel free to ignore it.