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 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
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 Chengjiana Biota of
Yunnan Province, China and just older than the Burgess Shale Fauna
of British Columbia, Canada. The specimens are often somewhat faint,
as here. The specimen has been water wet to heighten contrast in
the last photographs. Regardless, this is a rare specimen, little
seen outside of an academic collection. Most of the outcrops are
on BLM land which is not available for collecting. This material
however comes from a ranch on private land.
A New Soft-bodied Fauna: The Pioche Formation of Nevada, Bruce S.
Lieberman, Journal of Paleontology, Jul 2003.