In July 2022, Celsius Network (Celsius), a cryptocurrency (crypto) network, filed for bankruptcy. Celsius was a “crypto bank”: it took deposits in cryptos such as Bitcoin and Ether, promising a sizable yield to the depositors and then lending these out to institutional investors, or more aggressively, investing in decentralized finance (DeFi) protocols that were promising an even higher yield (but with a higher risk, of course). The case examines the centralized/hybrid and DeFi ecosystems and their key players, and it discusses building blocks such as stablecoins and their role in these ecosystems. The case can be taught in a course on financial institutions, capital markets, or financial technology (FinTech).