If you’re looking for a gang of vicious killers, look no further than the Apicomplexans. These single-celled protozoans cause death and destruction across the animal kingdom. They infect everything from butterflies to people. Their diseases include Texas Cattle Fever, toxoplasmosis, and the scourge that makes Plasmodium the baddest Apicomplexan of them all, malaria.

Scientists have named 6,000 apicomplexans, but they estimate there may be anywhere between 1.2 and 10 million species waiting to be identified. Every apicomplexan they’d studied so far is equipped with the same fearsome weaponry. Their cells are shaped like teardrops, and at the pointed end they have a ring of tubes, like the chambers on a revolver. When an apicomplexan prepares to invade a cell,