Borkum Stones ( Borkumse Stenen in Dutch, and Borkum Riffgrund in German) is a shallow, transboundary area shared between the Netherlands and Germany, and is one of the few remaining areas of natural geogenic reef in the southern North Sea. The seabed of Borkum Stones is heterogeneous, comprising a mix of hard substrates (ranging from cobbles and pebbles to large stones) surrounded by sand and gravel. This mosaic of substrates, in turn, supports a diverse benthic community with higher biodiversity levels than in neighbouring areas. Moreover, Borkum Stones is home to biogenic reefs formed by sand mason worm ( Lanice conchilega ), fragile structures that serve as important habitat for associated marine fauna. In 2007, the German side of the area was designated as a Natura 2000 site ( Borkum-Riffgrund ) , based on the presence of reefs and sandbanks, as well marine mammals, birds, and benthic invertebrates and fishes. Research surveys on the Dutch side of Borkum Stones have also revealed the presence of reefs ...