FIGURE 6 in Deep-sea serpulids (Annelida: Polychaeta) in tetragonal tubes: on a tube convergence path from the Mesozoic to Recent

FIGURE 6. Tube ultrastructures of Spirodiscus groenlandicus comb. nov. A–J: PIN 5485/12, A—longitudinal wall section, B—enlarged outer part with a layer consisting of large cigar-shaped crystals packed in bundles oriented in two directions, Cenlarged middle wall part consisting of small elongated crystals, D—enlarged middle (right) and inner (left) parts of tube wall, the latter consisting of very small consolidated isometric crystals, E—longitudinal wall section near tube mouth, F—tube crosssection, edges grouped by two, G—enlarged edge section, H—enlarged outer wall part, outer layer resembling a pile of isometric crystals, I—details of middle wall part, J—details of inner wall part. Arrows indicate direction of tube growth (where known). Abbreviations: o. s.—outer tube surface.