Pleurocystites

Pleurocystites (meaning rib bag or side bladder) is a genus of rhombiferan echinoderm (a cystoid) that lived in the Late Ordovician.

Its fossils are known from Europe and North America.

Pleurocystites grew to a height of 2 centimeters (3/4 of an inch) and fed on plankton.

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