Naturalis After Dark XXL Festival was an exciting science night for adults, at Naturalis in Leiden on the night of September 25. BioArt Laboratories was represented at the festival with a fascinating experiment where enthusiastic visitors offered the bacteria from their hands or keys, which were then imprinted on agar-agar in a petri dish. The project visualizes life on the human body and makes an attempt to show the cultural differences in habits from people from different places.