Demospongia have persisted as a major class of sponges since inception of the record of the phylum in the Cambrian. The class includes about 95% of all sponges in modern seas and all of the known freshwater forms, as well. These sponges occupy environments that range from warm, shallow subtidal, high energy to quiet, cold oceanic deeps. Demosponges range from exposed tide pool forms to cryptic dwellers and include the only boring sponges.