In 1880, J.G. de Man, one of the founders of nematology, took some samples of dune sand and saw a remarkable nematode, never seen before, which he described as Choanolaimus psammophilus. De Man focused on nematodes in natural systems as marine sediment, freshwater and wet brackish meadows in the surrounding of Leiden and in the south-west of the Netherlands (Zeeland). In the decennia after him the attention of nematologist was focused on plant parasitic nematodes which play an important role under agricultural conditions. Seventy years later, in 1949, the nematode was found for the second time. It appears that Choanolaimus is a common nematode in dune sand along the West-European coast, from Germany till Portugal. Based on the morphology, and confirmed by modern molecular methods Choanolaimus has no direct relatives, the closest are marine nematodes. It is a carnivorous nematode which consumes other nematodes as can be derived from the presence of stylets and spicula in the intestine. The spiral shaped structures are organs (amphids) which probably play a role in localizing their prey.