Cryptocurrencies don't have a physical analog such as coins or cash. They can be stored only online, but the private keys or other necessary information can be stored in several other ways.
Martijn Wismeijer had an xNT near-field communication (NFC) microchip injected into both hands and can now pay by just waving his hand. This method definitely has some disadvantages, though: you need to inject a chip in your body and always monitor if it's working properly. Anyway, it does look interesting.
We've talked about the Winklevoss brothers before. These crypto millionaires store their fortune on paper, using a pretty interesting method. They printed their wallet keys, split them into halves and hid them in safe deposit boxes in different locations. It's not the most convenient method, though it surely is a safe one.
Another unconventional way of storing bitcoins is in real coins. It's more of a thing for collectors than an actual means of payment, though. However, nothing stops you from storing your data this way.
But the true enthusiasts can go even further. The examples above are used by real people, but in theory, the private keys can also be stored in an image. For example, it can be a tattoo with all the necessary data or a picture on your wall with some hidden information.