Phylum Porifera Grant, 1836 - sponges Class Hexactinellida Schmidt, 1870 - hexactinellids Subclass Amphidiscophora Schulze, 1886 Order †Hemidiscosa Schrammen, 1924 [monotypic] 1 Family †Microhemidisciidae Finks & Rigby, 2004 [monotypic]