Phylum Porifera Grant, 1836 - sponges 1 Class Demospongea Sollas, 1875 see Class Demospongiae Sollas, 1885 2 Class Hexactinellida Schmidt, 1870 - hexactinellids 3 Class †Heteractinida de Laubenfels, 1955 4 Class Calcarea Bowerbank, 1864 - calcareous sponges 5 Family †Polyactinellidae Mostler, 1985 6 Family †Stromatidiidae Finks, 1960 7 Family †Tadassiidae Zhuravleva & Pyanovskaya, 1995