Grem'py

Grem'py (also referred to as Grem, Bones, Bone Pennies, and GP) is the international currency of the Mirkish nations. They are small, halcum coins, embossed with a depiction of a dragon skull. "Grem" and "py" translate to "bone" and "penny" respectively.
The reason for this name and design is due to Mirk'lin's history of valuing strength. In an ancient era, a person's place in Mirk'lin's social hierarchy was determined by their ability to slay monsters. This led to people collecting the bones of monsters as trophies, as well as a valuable trading commodity. The bigger the bones, the higher the value.
The people of Mirk'lin have since moved past the barbarous ways of their ancestors and adopted their modern coin-based currency, but the tradition of referring to their money as "grem" has persisted to this day.