fossil marine animal genera Linnaeus, 1758 - animals
   Phylum Porifera Grant, 1836 - sponges
     Class Hexactinellida Schmidt, 1870 - hexactinellids
       1 Order Hexactinosa Schrammen, 1903 see Order Hexactinosida Schrammen, 1903
       2 Order Lychniscosa Schrammen, 1903 see Order Lychniscosida Schrammen, 1903
       3 Order Lyssacinosida Zittel, 1877
       4 Order †Reticulosa Reid, 1958
       5 Order Amphidiscosa Schrammen, 1924 see Order Amphidiscosida Schrammen, 1924
       6 Order †Hemidiscosa Schrammen, 1924
       7 Order †uncertain