Actinosphaerium eichhornii (Ehrenberg, 1840) Stein, 1857
Diagnosis: Body usually spherical, sometimes cylindrical or flattened; cytoplasm usually with a discrete peripheral layer of large vacuoles; ecto- and endoplasm are clearly separated; diameter of the endoplasm more than twice the thickness of the ectoplasm; numerous nuclei, 20-500, scattered in the periphery of endoplasm, with some large central pieces of nucleolar material; axopodia granulated, large and thick, usually shorter than the body diameter; axonemes terminate on the nuclei or an electron-dense material near the nuclei; zoochlorellae sometimes present. Cyst with a mucous layer.
Dimensions: my measurements 30-2600 µm.
Ecology: fresh water, different kind of water types. Not rare. Feeding on algae, protists and even water fleas.