is a fossil demosponge
from the Cambrian
period. It was unusual because it was not attached to the sea bed, and radiated spines from the edge of its flattish, conical body, producing an appearance not unlike that of the peak of a big top
, with guy lines. Water entered the sponge parallel to the spines, being expelled, presumbaly, from a central openint. It reached 28mm in diameter.
Fossils of Choia have been found in the Burgess Shale in British Columbia, the Maotianshan shales of China and the Wheeler Shale in Utah.