Cretaceous sponges from the Campanian of Misburg and Höver
Leptophragma pusillum has not been reported by Schrammen (1910-1912, 1924) from Misburg or Höver, only from Oberg. It appears to be moderately common in some Lower Campanian strata.
The specimen shown is the only one showing a short stalk and small roots. Usually, only the cylindrical upper parts, as the one shown in the second picture, are found.
Leptophragma micropora is moderately common, but very fragile since the wall thickness is only about 1 mm. Complete funnels as the one shown here in side- and bottom-view are thus very unusual.
The broad folds in the funnel are very characteristic for Leptophragma micropora and are thought to be a primary feature, i.e. not due to deformation.
Photomicrographs of Leptophragma micropora. (Etched samples, reflected light.)
The first two images show the arrangement of epirhyses in the dermal wall of Leptophragma micropora. The top image is a view of the dermal surface from outside the sponge. The dermal hexactines are mantled and fortified by additional silica. The gastral side is similarly reinforced, while the skeletal layer in the middle is weak. Therefore, upon etching, the thin wall of Leptophragma always gets cleaved into two halves (similar to Laocoetis). The second picture is a view onto the cleavage plane of the dermal layer (same fragment as in the image above). It shows strands of hexactines running in longitudinal direction. The third image is an enlarged view of the latter.
The next two images show some details of the dermal skeleton and the dictyonal skeleton of Leptophragma micropora. Notice the difference between the smooth dictyonal and the reinforced dermal hexactines.