Light (A, B) and scanning electron (C-I) micrographs of Difflugia urceolata. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Lateral view. (E) Latero-apertural view. (F) Apertural view. (G) Close up view of aperture to show its regular outline. (H) Lateral view of apertural region to illustrate the surrounding collar made of small quartz particles. (I) Portion of shell to show arrangement of particles and rough surface of the shell.