Fig. 4 in New serpulid polychaetes from the Permian of western Sicily

Fig. 4. Serpulid polychaete "Serpula" prisca sp. nov. (holotype PMC. S 5.15.09.2017) from the Wordian to upper Permian, "Pietra di Salomone" Limestone, Sicily, Italy. A. Central portion of the tube glued together, with only feeble growth lines on its outer surface. B. Tube wall with large secondary calcite crystals pointing to complete recrystallization. C. Close-up of outer surface showing very thin and smooth growth lines. D. Magnification of C, with closely spaced, relatively prominent growth lines, crossed by nearly imperceptible longitudinal striations. All SEM images.