''Choia'' is a genus of

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

demosponge Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include 76.2% of all species of sponges with nearly 8,800 species worldwide (World Porifera Database). They are sponges with a soft body that covers a hard ...

ranging from the

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

until the Lower Ordovician periods. Fossils of ''Choia'' have been found in the Burgess Shale in British Columbia; the Maotianshan shales of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

; the Wheeler Shale in Utah; and the Lower Ordovician

Fezouata formation The Fezouata Formation or Fezouata Shale is a geological formation in Morocco which dates to the Early Ordovician.

. It was first described in 1920 by Charles Doolittle Walcott. Choia carteri reconstruction

Life habit

''Choia'' was originally thought to be not attached to the sea bed: the living animal was originally thought to rest directly on the substrate, with the radiating spines from the edge of its flattish, conical body, giving an appearance not unlike that of the peak of a big top, with

guy line A guy-wire, guy-line, guy-rope, or stay, also called simply a guy, is a tensioned cable designed to add stability to a free-standing structure. They are used commonly for ship masts, radio masts, wind turbines, utility poles, and tents. A ...

s. Recently discovered fossils from Lower Ordovician Morocco show that the living animal was actually suspended high above the seafloor, attached via stalk-like spines derived from spicules. Water is assumed to have entered the sponge parallel to the spines, being expelled, presumably, from a central opening. Species reached up to an average of 28 mm in diameter.

Presence in the Greater Phyllopod Bed

127 specimens of ''Choia'' are known from the Greater Phyllopod bed, where they comprise 0.2% of the community.

References

External links

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Picture of ''C. utahensis'' fossil
Burgess Shale fossils Burgess Shale sponges Maotianshan shales fossils Protomonaxonida Early Ordovician extinctions Prehistoric sponge genera Sirius Passet fossils Cambrian first appearances Taxa named by Charles Doolittle Walcott Fossil taxa described in 1920 Early Ordovician genus extinctions Wheeler Shale {{demosponge-stub Cambrian genus extinctions Ordovician genus extinctions