Light (A, C) and scanning electron (B, D-I) micrographs of Arcella gibbosa. (A, B) View of many specimens showing variability in shape and size of the shell. (C) View of live specimen illustrating numerous short epipodes and two typical vesicular nuclei with one large central nucleolus. (D) Latero-apertural view to show smooth apertural surface and invagited aperture. (E) Dorsal view showing depressed segments of the surface. (F) Lateral view. (G) Close up view of aperture to show distinct apertural lip. (H) Close up view of aboral side showing depressed segments of the surface. (I) Portion of shell surface showing small organic alveoli and numerous surrounding small pores.