Like all echinoderms, sea cucumbers have an endoskeleton just below the skin, calcified structures that are usually reduced to isolated microscopic ossicles (or sclerietes) joined by connective tissue. In some species these can sometimes be enlarged to flattened plates, forming an armour. In pelagic species such as the Sea Cucumber , the skeleton and a calcareous ring are absent.
The sea cucumbers are named for their resemblance to the vegetable cucumber.