As part of its morning routine, the marine alga Nitzschia cf pellucida produces a chemical that annihilates nearby microbial competitors. Researchers led by Wim Vyverman of Ghent University, in Belgium, and Georg Pohnert of Friedrich Schiller University of Jena, in Germany, discovered that among the noxious brominated and iodinated molecules in the diatom’s toxic arsenal is cyanogen bromide, N≡C–Br (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1108062109). This compound was used as a chemical warfare agent during World War I, but it hadn’t previously been found in nature. To show that the alga produces NCBr, the team fed samples 13C to see if the radiolabel would end up in the chemical weapon—it did. The team is not yet sure how the alga sources its cyanide, but they suggest amino acid metabolism as an option. The researchers also propose that NCBr kills nearby microorganisms by destroying the machinery they need for photosynthesis, as well as destroying membranes and incapacitating essential enzymes. They don’t know how N. cf pellucida manages to evade damage itself, a feat they are now exploring.