Figure 6. A–D in Ultrastructure and mineral composition of serpulid tubes (Polychaeta, Annelida)

Figure 6. A–D, Spirobranchus giganteus, polished, and treated with GA solution for 5 min. A, outer tube layer with oriented fibrillar structure, cross section. B, outer tube layer, oriented fibrillar structure, longitudinal section. C, detail of (B), showing the close-up of the organic sheet. D, outer layer with spherulitic irregularly oriented prismatic structure; note the epitaxial growth of prisms through several organic sheets. E, Ficopomatus enigmaticus, polished longitudinal section, spherulites in irregularly oriented prismatic structure, treated with 1% acetic acid for 2 min. F, Placostegus tridentatus, calcitic spherulite, longitudinal section of the tube with simple prismatic structure. Abbreviations: exter, exterior; ginc, growth increments; osh, organic sheet; pr, prismatic crystals; SPH, spherulite.