Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Clade neomura Cavalier-Smith, 1987
             Domain Eukaryota Chatton, 1925 - eukaryotes
               "protists" incertae sedis
                 Group †Calcitarcha G.J.M. Versteegh, T. Servais, Streng, Munnecke & Vachard (2009), incertae sedis [polyphyletic] - calcispheres
                   Genus †Schizosphaerella Deflandre & P.J.L. Dang. (1938)