Sponge Fossil Crumillospongia from Wheeler Formation

The Demosponge Crumillospongia belong to the family Hazeliidae. Because no attachment structures have ever been found, it remains enigmatic whether this early Poriferan lived attached to the seafloor. Crumillospongia are somewhat rare in the Middle Cambrian of Utah, and very rare in the Burgess Shale. The Crumillospongia sponges on this plate have unusually good contrast.

Sponge fossils from the Cambrian Explosion are found in various Cambrian sites in North America, most notably the Burgess Shale of Canada, and the Cambrian stratigraphy of House Range of Utah, like this specimen from the Wheeler Formation. Many sponges are also described from the Chengjiang biota of China. Sponges are believed to have undergone repeated radiations during the Phanerozoic, and probably attained their greatest diversity during the Cretaceous.

Also See: Utah Cambrian Explosion Fossils