Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Clade neomura Cavalier-Smith, 1987
             Domain Eukaryota Chatton, 1925 - eukaryotes
               Clade discaria Cavalier-Smith, 2021
                 Clade dorsates Cavalier-Smith, 2021
                   Clade podiates Cavalier-Smith, 2012
                     [crown] Clade Amorphea Adl et al. 2012 [Simpson, Medina & Adl 2020]
                       [crown] Clade Obazoa Brown, Sharpe, Silberman, Heiss, Lang, Simpson & Roger 2013
                         [crown] Clade Opisthokonta Cavalier-Smith 1987 [Simpson & Medina 2020] - animal-fungal clade
                           Superkingdom Holozoa Lang, O'Kelly, Nerad, Gray & Burger, 2002
                             Clade filozoa Shalchian-Tabrizi, Minge, Espelund, Orr, Ruden, Jakobsen & Cavalier-Smith, 2008
                               Kingdom Animalia Linnaeus, 1758 - animals
                                 Clade Planulozoa Wallberg, Thollesson, Farris & Jondelius 2004
                                   Subkingdom Bilateria Hatschek, 1888 - bilaterians
                                     Clade Nephrozoa Jondelius, Ruiz-Trillo, Baguñà & Riutort 2002
                                       Infrakingdom Deuterostomia Grobben, 1908
                                         [crown] Clade Ambulacraria Metschnikoff 1881 [Halanych 1995]
                                           Phylum Echinodermata Bruguière, 1789 - echinoderms
                                             Subphylum Eleutherozoa Bell, 1891
                                               Infraphylum Echinozoa Haeckel, in Von Zittell, 1895
                                                 Class Echinoidea (Leske, 1778) - sea urchins and sand dollars
                                                   Subclass Euechinoidea Bronn, 1860
                                                     Superorder Echinacea Claus, 1876
                                                       Order Arbacioida Gregory, 1900
                                                         Family Arbaciidaeᵀ Gray, 1855
                                                           Genus Arbaciaᵀ Gray, 1835
                                                           Genus Arbaciella Mortensen, 1910
                                                           Genus Coelopleurus Agassiz, 1838
                                                           Genus Habrocidaris Agassiz & Clark, 1907
                                                           Genus Podocidaris Agassiz, 1869
                                                           Genus Tetrapygus Agassiz, 1841