Cretaceous sponges from the Campanian of Misburg and Höver
? Discoptycha simplex
Discoptycha simplex was first described from the Coniacian of Rumilly-en-Cambrésis (Northern France) by Simone Defretin-Lefranc (1961). Two poorly preserved specimens probably identical with Discoptycha simplex have been recovered from the Lower Campanian of Höver in 2006 and 2007. They are probably the only reports of the species outside the type locality so far.
The specimen of ?Discoptycha simplex shown in the picture is exposed from the underside, as indicated by several roots (not to be confused with several spines of a regular urchin in the top right). It consists of a thin (2 mm), radially folded sheet forming a shallow dish. The folds bifurcate symmetrically near the center, or asymmetrically, i.e. as short side folds perpendicular to one side of a primary radial fold. The folds tend to form narrow ribs on the underside, and broad ridges on the upper surface of the sponge. The roots are thin (3 mm), long (50 mm) tubes of a dense and irregular meshwork derived from the cortical layer. They are very similar to the roots of Becksia soekelandi and Marshallia tortuosa.
The dictyonal skeleton is made up uf a very regular cubic, lychniscoid meshwork approximately 5 meshes thick. The gastral and dermal surfaces show cortical layers which have been largely lost, probably due to frost action. In both cases the cortex is formed by a silica mantle, covering the outermost lychnisk beams. The silica mantle transforms half of the quadratic mesh apertures to round pores with diameters only slightly less than the mesh width, while the other half is further subdivided to form several (usually two to four) smaller voids. In general, the open and filled meshes are arranged in quincunx, but some disorder may be present.