Beta‐lactam biosynthesis was thought to occur only in fungi and bacteria, but we recently reported the presence of isopenicillin N synthase in a soil‐dwelling animal, Folsomia candida . However, it has remained unclear whether this gene is part of a larger beta‐lactam biosynthesis pathway and how widespread the occurrence of penicillin biosynthesis is among animals. Here, we analysed the distribution of beta‐lactam biosynthesi...