FIGURE 15 in Deep-sea serpulids (Annelida: Polychaeta) in tetragonal tubes: on a tube convergence path from the Mesozoic to Recent

FIGURE 15. Tube ultrastructures of fossil tetragonal serpulids from the Middle Jurassic. A-D: Nogrobs cf. vermicularis PIN 5485/18. A—longitudinal wall section, B—enlarged outer part consisting of consolidated crystal aggregates, crystal growth lines are visible; C—enlarged middle wall part containing irregularly-shaped and isometrical crystals; D—enlarged middle (left) and inner (right) wall parts. E-H: Glandifera cf. vertebralis, PIN 5485/03. E—longitudinal wall section; F—enlarged outer to middle part consisting of consolidated aggregates in the outer part, with appearance of isometric crystals in the middle part; G—enlarged middle part of the wall, containing irregularly-shaped and isometrical crystals; H—enlarged inner part of tube wall. Arrows indicate the direction of growth and placed along the axis of parabolic growth lamellae, dashed line marks the inner margin of tube wall. Abbreviation: o. s.—outer tube surface.