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Genus Pyxidicula

Shell is round in frontal view, hemispheric in lateral view; shell wall areolate, composed of organic, hollow building units, which in older, brown specimens become filled with inorganic material like manganese. Aperture is almost as wide as the diameter of the shell, apertural rim is usually recurved outside. One vesicular nucleus. Ecology: freshwater, soils. Type species: Pyxidicula operculata (Agardh, 1827) Ehrenberg, 1834