English Stereom Cited by user Ornithopsis on 08 Apr 2020 Stereom is a calcium carbonate material that makes up the internal skeletons found in all echinoderms, both living and fossilized forms.
English Ctenoimbricata Cited by user Ornithopsis on 08 Apr 2020 Ctenoimbricata is an extinct genus of bilaterally symmetrical echinoderm, which lived during the early Middle Cambrian period of what is now Spain.