Paleozoic sponges

Choia is a genus of extinct demosponge ranging from the Cambrian until the Lower Ordovician periods. Fossils of Choia have been found in the Burgess Shale in British Columbia; the Maotianshan shales of China; the Wheeler Shale in Utah; the Itajaí Basin in Brazil; and the Lower Ordovician Fezouata formation. It was first described in 1920 by Charles Doolittle Walcott.

Vauxia is an extinct genus of demosponge that had a distinctive branching mode of growth. Each branch consisted of a network of strands. Vauxia also had a skeleton of spongin (flexible organic material) common to modern day sponges. Much like Choia and other sponges, Vauxia fed by extracting nutrients from the water.

Hazelia is a genus of spicular Cambrian demosponge known from the Burgess Shale, the Marjum formation of Utah, and possibly Chengjiang. It was described by Charles Walcott in 1920.