P. infercambriensis is the geologically oldest known radiodont; its remains date to the third age of the Cambrian. The type and only known specimen, a partial appendage, was found in a core sample from a borehole nearly five kilometers deep in northern Poland. P. infercambriensis was previously regarded as belonging to a separate genus, Cassubia, named after the historical region of Kashubia in which the specimen was found, but Cassubia is now considered a junior synonym of Peytoia.
