Project CRESCO Citizen Rescuers for Collections brings together for the first time a team of Belgian biology researchers and curators from the AfricaMuseum (Tervuren) and from the Institute of Natural Sciences (Brussels), and 26 citizen scientists. They join forces to make hidden biological collections data accessible. Either by taking standardized photos of specimens, which can help researchers worldwide describe a species without visiting the museums, or by transcribing hundred-year-old handwritten collection labels, the ones that even the best OCR programs cannot deal with. CRESCO has pioneered hybrid, online and on-site, citizen science approaches. The project has strengthened the citizen science community of the two museums by achieving gender equality and by reaching out to Ukrainian refugees. It has delivered quality scientific data that couldn t have been obtained otherwise.