Figure 4. A–B in Ultrastructure and mineral composition of serpulid tubes (Polychaeta, Annelida)

Figure 4. A–B, Protula diomedeae, semi-ordered irregularly oriented prismatic structure. A, cross section. B, longitudinal section. C–D, Pyrgopolon ctenactis, semi-ordered spherulitic irregularly oriented prismatic structure, outer tube layer. C, cross section. D, longitudinal section. E–F, Crucigera websteri, contact of inner tube layer with spherulitic prismatic structure, and third tube layer from outside with lamello-fibrillar structure. E, cross section. F, longitudinal section. All samples were polished and treated with 1% acetic acid for 2 min. Abbreviations: exter, exterior; ginc, growth increments; LF, lamello-fibrillar structure; osh, organic sheet; SPHP, spherulitic prismatic structure.