Nestled at the heart of the French national museum of natural history (MNHN) in Paris, the Communication Molecules and Micro-Organism Adaptation (MCAM) laboratory, a joint CNRS-MNHN unit, is home to some precious samples. Over a century old, they have just been cleaned and inventoried by the laboratory’s team. Christine Maulay-Bailly, technical manager of the chemical library, presents a selection.