Every cash bill has an identifier and can be tracked. No two have the same ID. They are regularly pulled in and replaced. Some are also marked, in other ways, to follow their movements. Bank money and credit is tracked through ledgers, so that is arguably more fungible, but highly traceable. What the latter has is a gigantic market, so that one could create a complex movement of the money, to obfuscate the origins.

Gold is an element and can be made untraceable and unidentifiable through melting, stretching, stamping, or otherwise reforming.