Fig. 7. Longitudinal section through the well preserved specimen PIMUZ 28583 in Devonian pearls and ammonoid-endoparasite co-evolution

Fig. 7. Longitudinal section through the well preserved specimen PIMUZ 28583 of Sellanarcestes spp., Sellanarcestes wenkenbachi Zone, Emsian, Oufrane (S of Tata), Morocco. A. +/− median section displaying many "Housean pits", most with internal tube; overview. "Housean pits" are marked by white arrows. B. Three closely spaced pits, two displaying the internal tubes, the remaining void inside the pit is filled with a fine−grained sparitic matrix, note the continuous ammonoid shell layer covering the pits and the septum, which grew on the pit wall, note the distinguishable shell layers, which are recrystallised to varying degrees. C. A corroded pit with tube, note the continuation of the innermost ammonoid shell layer. D. Two adjacent fused pits, only the right pit shows the delicate internal tube, mural part of septum on the left.