The fossil, that dates back some 400 million years, was discovered in Tongzi County while the scientists were studying a geological section in the area, according to the county government, Xinhua news agency reported.
With an egg-shaped body, cystoids are echinoderms, marine invertebrates that existed during the Pleozoic Era, the Ordovician and Silurian Periods, and became extinct during the Devonian Period.
Guizhou boasts a rich store of prehistoric treasures. Fossils of various extinct invertebrate marine species have been discovered in the area. Tens of thousand of vertebrate fossils have also been found there.