Capsospongia is interpreted to be an early orchoclad anthaspidellid at the base of the demosponges (Rigby, 1986). Demosponges, the same group that are harvested as bath sponges, represent the largest class of sponges today.
Capsospongia – from the Latin capsa, “boxed” or “encapsulated,” and spongia, “sponge.”
undulata – from the Latin undulatus, “wavy,” after its undulating edges.
Burgess Shale and vicinity: none.
Other deposits: none.
The Walcott Quarry on Fossil Ridge.
Originally described as Corralia undulata by Charles Walcott (1920) based on two specimens, Capsospongia was later redescribed as a separate genus (Rigby, 1986). A third specimen collected by a Royal Ontario Museum expedition was described in 2004 by Rigby and Collins.
Capsospongia is 35-75 mm tall and tapering up to around 20 mm in maximum width. Attached to the substrate by a narrow (3-4 mm wide) base, it has a curving, conical form with a wide open top (osculum) through which water would have been expelled. Combined with its annulated surface, which is ornamented by a series of low, length-parallel ridges and grooves, the organism somewhat resembles a rugose coral (Shapiro and Rigby, 2009). Major canals run parallel to the ridges, connected by a less ordered network of smaller channels within its thin walls, terminating into small pores (ostia) through which water would have been inhaled.
Capsospongia is known from a handful of specimens (Rigby and Collins, 2004).
Capsospongia stood anchored to the sea floor. Particles of organic matter were extracted from the water as they passed through canals in the sponge’s wall.
RIGBY, J. K. 1986. Sponges of the Burgess Shale (Middle Cambrian), British Columbia. Palaeontographica Canadiana, 2: 1-105.
RIGBY, J. K. AND D. COLLINS. 2004. Sponges of the Middle Cambrian Burgess Shale and Stephen Formations, British Columbia. Royal Ontario Museum Contributions in Science, 1: 1-155.
SHAPIRO, R. S. AND J. K. RIGBY. 2009. First occurrence of an in situ anthaspidellid sponge in a dendrolite mound (Upper Cambrian; Great Basin, USA). Journal of Paleontology, 78(4): 645-650.
WALCOTT, C. D. 1920. Middle Cambrian Spongiae. Smithsonian Miscellaneous Collections, 67(6): 261-364.