CRISPR claimed scientific fame for its ability to quickly and accurately edit genes. But, at the core, CRISPR systems are immune systems that help bacteria protect themselves from viruses by targeting and destroying viral DNA and RNA. A new study published in Science reveals a previously unrecognized player in one such system—a membrane protein that enhances anti-viral defense—simultaneously broadening our understanding of and raising more questions related to the complexities of CRISPR.