The Demosponge Crumillospongia belong to the family Hazeliidae.
Because no attachment structures have ever been found, it remains
unclear whether or not this early poriferan lived attached to the
seafloor. Crumillospongia are somewhat rare in the Middle Cambrian
of Utah and Nevada, and very rare in the Burgess Shale. The genus
derives its name from the resemblance of the sponge to a purse,
while the specific name refers to the fact that the sponge has pores
of two sizes.
fossils from the Cambrian Explosion are found in various Cambrian
sites in North
America, most notably the Burgess
Shale of Canada, and the Cambrian
strata of Utah, unlike this specimen, which comes from a new
location. Many sponges are also described from the Chengjiang
biota of China. Sponges are believed to have undergone repeated
radiations in the Phanerozoic, and probably attained their largest
diversity in the Cretaceous.
one comes from the Comet Shale Member of the Pioche Formation of
Nevada. This deposit spans the transition of Early to Middle Cambrian
which saw the extinction of the Olenellid trilobites. It is just
younger than the comparable material from the Chengjiang
Maotianshan Shales of Yunnan Province, China and just older
than the Burgess Shale Fauna of British Columbia, Canada.