Вероятно, мы нашли категорию простейших по вашему запросу:

Genus Schoenbornia

Shell is ovoid, circular in cross section, hyaline, transparent; composed of collected idiosomes of small euglyphids, angular quartz and amorphous siliceous elements. Schönborn et al. (1987) suppose that the latter are produced by amoebae, but this remains unproved. Aperture is terminal, circular. Ecology: soils. Type species: Schoenbornia humicola Schönborn, 1964. Note: Heleoporella Coûteaux, 1978 is probably a synonym of this genus.