We've learned that everything from sea shells over salt to silver coins were once money. Some of those "moneys" did their job better than others but all were products of their time and served their purpose. They were the tools at hand serving in the functions of  "being a medium of exchange", "storing value" and  "being a unit of account".

To get to this functionality the tool of money should have a few characteristics. Checking for these characteristics can be our checklist to compare moneys.