'Er was eens'  is a series of six documentaries on the Royal Belgian Institute of Natural Sciences (RBINS) and the scientists working there. 

Approached from a philosophical angle, the series addresses all the aspects of fundamental research. Besides the famous natural history museum, the RBINS has a collection of no less than 37 million specimens, all carefully stored in a mysterious tower overlooking Brussels. It is a collection that aims to welcome the history of Earth and life. It makes up the playground of almost 250 scientists. Their main job is to map life on Earth, from the smallest cell to the biggest dinosaur. A diverse community in which biologists, geologists, mineralogists, palaeontologists, anthropologists, oceanographers, engineers and computer scientists find within the collection an endless source of information and astonishment. The institute is also their base of operations when they leave to conduct research around the world.