Currency

Long ago during the first era of Man the various kingdoms minted many different symbols and emblems upon their coinage. One kingdom, who traded heavily with dwarves and were inspired by their traditions, began etching symbols of prominent magical creatures on their coins. Over time the convention spread and became popular among merchants across the lands, and eventually all human kingdoms took up the symbols. As the main go-betweens of humans and dwarves, the gnomes played a key role in adopting a common currency (not only in symbology, but also weight, size, etc.). While various kingdoms still minted their own varieties and added their own flare, the basic designs stayed the same. The practice has become so commonplace, that even the great kingdoms of dwarves have adopted the same symbology.

Platinum Dragons
In the image of the revered platinum dragon Bahamut, the most valuable coin carries the image of a dragon.

One Platinum Dragon is worth ten Golden Griffons.

Golden Griffons
Another of the great magical flying creatures, the fearsome but noble griffon graces the most used coin for trade among merchants, the gold piece.

One Golden Griffon is worth ten Silver Serpents.

Silver Serpents
On the faces of the coin most used by commoners, the silver piece features a generic serpent, in homage to the many magical non-dragon serpentine creatures of the world - Naga, Couatl, Yuan-ti, (to a lesser extent the other reptilian races lizardmen, trogladytes) etc.

One Silver Serpent is worth ten Copper Centaurs.

Copper Centaurs
The good but reclusive centaur is found on the most widespread but least valuable coin, the copper piece.

Ten Copper Centaurs is worth one Silver Serpent.