Biologists sometimes use the phrase “arms race” to describe an evolutionary tug-of-war, but it’s rarely this literal. Microbes called dinoflagellates (above) have developed intricate weapons—including a microscopic version of a Gatling gun—to harpoon their dinners, a new study shows. Scientists have known about these harpoons for decades, and some have guessed that the weapons stem from the same source as the ones wielded by jellyfish and other cnidarians. An analysis of the genes and proteins involved with weapon construction, however, shows that dinoflagellates and cnidarians use different proteins to manufacture their weapons—meaning they arrived at similar solutions through separate evolutionary paths, researchers report today in Science Advances. In fact, 3D scans of dinoflagellate harpoons reveal a level of complexity that far outstrips that jellyfish and their relatives. In one dinoflagellate species (Polykrikos lebouriae), a pointed projectile rips a hole through the weapon’s capsule on its way out, and a tether keeps the harpooned prey close. Another (Nematodinium) sports a harpoon arranged like a Gatling gun that can shoot up to 15 projectiles. That’s the first example of a multibarreled weapon in nature, an incredibly complex hunting tool for such a tiny organism. As their prey evolved better defenses, dinoflagellates seem to have responded by simply packing more and more firepower.