In microbial mats, communities of microorganisms live among viruses that infect them. But what trends govern those virus-host interactions? Do generalist viruses run rampant, capable of infecting different host species? Or, do they tend to specialize, infecting just a single host? Another wrinkle in the mystery is that viruses can affect their prey in different ways. They have the capacity to kill outright, replicating so thoroughly that they lyse the cell—a process called lytic infection. But some viruses are also able to play a long game. In a lifestyle called lysogeny, they can insinuate themselves inside the host's genome, living quietly and replicating with their host indefinitely.