Вероятно, мы нашли категорию простейших по вашему запросу:



Genus Pseudawerintzewia

Shell is oviform, circular in cross section; mainly composed of small siliceous plates, pasted together with abundant brown organic cement and arranged so that the shell surface appears smooth. Aperture is terminal in fattened center of the broader end, small, elliptical or circular, thickened lip, no collar. Ecology: soils. Type species: Pseudoawerint-zewia calcicola Bonnet, 1959