Dirt Money

Dirt Money was the currency of the civilization of Mars, before the disaster struck.

Description
Like all aspects of their civilization, their currency is based on the plant cycle and therefore is made from the fertile of the more long-lived groves, rendering it much more valuable to them. Like all aspects of the martian life cycle, it also holds actual information, even further explaining the worth it held to them. In Martian Dreams, the Avatar had to find some dirt money for the Xorinite Wisp in the Abandoned City in order to learn more about Mars and its civilization. As the Wisp claimed, the structure of the Dirt Money was such that it could hold valuable information even after the long time. 

Trivia

 * Dirt money can be found in the mines where the Avatar frees the two explorers from the cave-in in order to get access to Olympus.