Phylum Porifera Grant, 1836 - sponges Class Demospongea Sollas, 1875 see Class Demospongiae Sollas, 1885 Subclass Clavaxinellida Lévi, 1956 Order Protomonaxonida Finks & Rigby, 2004 Family †Mahalospongiidae Rigby & Stuart, 1988 [monotypic] 1 Genus †Mahalospongia Rigby & Stuart, 1988