Bitcoin isn’t like traditional currencies, and not just because it doesn’t exist as actual coins or paper banknotes.

Unlike traditional currencies like the dollar or euro, Bitcoin isn’t controlled by a single government or central bank. Instead, every transaction involving the popular cryptocurrency is logged in a computerized public ledger called a blockchain. This collection of receipts is maintained on millions of devices around the world in individual collections called blocks. Each time there’s a transaction involving Bitcoin, an anonymous data “fingerprint” appears in a block recording the exchange.

This key innovation is the basis for “Block Bills,” a collection of paper banknotes that bring the virtual payment system into the real world. As works of art, the whimsical bills have no monetary value. But they provide a “map” to the inner workings of the Bitcoin system—and they have a subtle beauty all their own.

“In some way, the project is a loose data visualization, but I mainly wanted to make the bills be interesting on their own as artworks,” says Matthias Dörfelt, the Los Angeles-based artist who made the notes.