Fungi produce metabolites that humans have used to improve health. For example, they secrete penicillin, which is then purified and used as an antibiotic for humans, leading to the development of many other antibiotics. However, the ecology of fungal metabolites in microbial communities is not well understood. In a new study, researchers use cheese rinds to demonstrate that fungal antibiotics can influence how microbiomes develop. The study is published in mBio.