Demospongiae

thumb| The carnivorous ping-pong tree sponge, Chondrocladia|Chondrocladia lampadiglobus thumb|Monanchora arbuscula ([[Poecilosclerida)]] thumb|Geodia barretti ([[Tetractinellida)]] thumb|Chondrosia reniformis ([[Chondrosiida)]] thumb|Spongia officinalis ([[Dictyoceratida)]] thumb|Spongilla lacustris ([[Spongillida)]]

Demosponges or common sponges are sponges of the class Demospongiae (from + ), the most diverse group in the phylum Porifera which include greater than 90% of all extant sponges with nearly 8,800 species worldwide (according to the World Porifera Database). Being siliceous sponges, they are predominantly leuconoid in structure with an endoskeleton made of a meshwork of spicules consisting of fibers of the protein spongin, the mineral silica, or both. Where spicules of silica are present, they have a different shape from those in the otherwise similar glass sponges. Some species, in particular from the Antarctic, obtain the silica for spicule-building from the ingestion of diatoms.