They are believed to be one of the earliest-diverging branches of echinoderms, with their bilateral symmetry a trait shared with other deuterostomes.

It was located at the posterior end, defining a clear anterior-posterior body axis unlike other echinoderms.

[4] All ctenocystoids had a ctenoid apparatus, a comb-like arrangement of movable plates at the anterior end of the animal.

[1] Courtessolea Jugoszovia Conollia Pembrocystis Etoctenocystis Gilcidia Ctenocystis Ctenocystoids are likely among the most basal stem-group echinoderms.

[7][8] The presence of stereom plates indicates that they most likely belong to the echinoderm total group, rendering a hemichordate affinity unlikely.