All of the previously known CRISPR immune systems protect bacteria by deactivating genes from an invading virus. Now, a recently discovered CRISPR protein, called Cas12a2, has been found to act as a kind of multi-purpose self-destruct system for bacteria, capable of degrading single-stranded RNA, single-stranded DNA and double-stranded DNA. This ability could lead to a new approach to developing diagnostics for diseases such as COVID-19 and the flu.