Microorganisms were first described by van Leeuwenhoek in the 17th century. Later, Pasteur and Koch related them to diseases. Since then, the scientific community has striven to extend awareness of the many junctions of microorganisms. Science museums provide an excellent setting in which to disseminate such knowledge, but the presentation of living microorganisms is a challenge. We describe an approach to the exhibition of living microorganisms pursued in a science museum in Barcelona (CosmoCaixa Barcelona). In two exhibits, the museum shows photosynthesis in cyanobacteria and Winogradsky columns, which provide an example of living microbial ecosystems.