Pleurostoma radiata
F.A. Roemer 1840
Pleurostoma radiata is a rare sponge at Misburg and Höver. It forms thin-walled bilaterally compressed (scabbard-like) tubes (picture below) to fan-shaped compressed funnels (picture). Along the narrow edges, the tube walls are perforated by oval openings, 5 to 10 mm wide. The outer surface of the sponge shows numerous small pores (ostia) which are arranged in a very regular and characteristic, bilaterally symetrical pattern of radiating rows (see pictures).
The specimen in the picture has a preserved upper rim, which is slightly wavy. Note also the large openings, visible along the right-hand edge.
Scabbard-like shape of Pleurostoma radiata. Lower part missing, only negative preserved.
Pleurostoma radiata can be confused with Typhlopleura dichotoma and with Guettardia.
Fan-shaped specimen, tentatively identified as Pleurostoma radiata.
The specimen does not show any openings along the narrow edges. It is very thin (3 mm only) and has a finer skeletal meshwork and pore pattern compared to the other examples of Pleurostoma radiata known to the author. - Could represent a new species.