Light (A) and scanning electron (B-I) micrographs of Difflugia ampullula. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C-D) Lateral view of two specimens showing regular outline and smooth shell surface. (E-F) Latero-apertural view to illustrate small collar. (G) Apertural view to show irregular edge of the collar. (H) Lateral view of apertural region. (I) Portion of shell surface to show arrangement of particles and small areas of organic cement in form of a network of small meshes.