Syltrochos pyramidoidalis Von Hacht, 1981
Discussion — Specimens of Syltrochos pyramidoidalis Von Hacht, 1981, were, until recently, known exclusively as erratics (Rhebergen, 2009). Their age was established based upon co-occurring guide fossils, such as trilobites and brachiopods (Krueger, 1990), which indicate the Baltic regional Jöhvi Substage (D1 ) to Keila Stage (D2 ). As a result of intensive silicification, spicules were dissolved by chalcedony, skeletal structures devistated and only the canal system was recognisable. As a result, Finks & Rigby (2004) assigned Syltrochos as an endemic genus in open nomenclature to uncertain order and family. However, new material from the Dutch-German border region revealed the skeleton to be composed of spheroclones. On account of this characteristic, Syltrochos pyramidoidalis Von Hacht, 1981, has to be assigned to the family Astylospongiidae von Zittel, 1877.