A remarkable new Middle Sandbian (Ordovician) hexactinellid sponge in Baltic erratics

A new species of complex hexactinellid sponge, Haljalaspongia inaudita, is described from fluvially transported blocks found in northwestern Germany, near the Dutch border, but which probably originated from the eastern Baltic region. The heavily folded wall is composed of multiple spicule layers, including dermal and gastral layers of acanthohexactines, and a central layer of sub-parallel monaxons. The monaxial layer is lined on one side by a reticulate array of smooth monaxons. The sponge is difficult to assign to any known fossil or recent group, but shares some features with the dictyospongioid family Docodermatidae.