Before revision: Such physical structures are the commonly referred "skeletons", which may be internal (as in vertebratess , echinoderms and sponges) or external (as in arthropods and non-coleoid molluscs).
After revision: Such physical structures are the commonly referred "skeletons", which may be internal (as in vertebrates , echinoderms and sponges) or external (as in arthropods and non-coleoid molluscs).