why echinoderms are often called living, moving castles.
Echinodermata: Morphology. Echinoderms have been compared to living, moving castles. Castles are made of interlocking blocks, with a single main entrance and numerous slit windows for air and for defense.Echinoderm skeletons are made up of interlocking calcium carbonate plates and spines.This skeleton is enclosed by the epidermis and is thus an endoskeleton.astles are made of interlocking blocks, with a single main entrance and numerous slit windows for air and for defense. Echinoderm skeletons are made up of interlocking calcium carbonate plates and spines. This skeleton is enclosed by the epidermis and is thus an endoskeleton.