Australian money is some of the most advanced currency in the world: not only is it completely waterproof, but it's notoriously hard to counterfeit due to its complex design.
Apart from its acceptance, good money also requires portability. If people can carry or transfer money from one place to another, then it is good money.
The ability to recognize money is critically important. Today, we can look at a currency note and tell its value. If money is not cognizable, then people can find it difficult to determine if they are dealing with money or some inferior asset.