Echinoderm is the name given to marine animals whose adults are acknowledged to possess usually five-point radial symmetry, which is the balance of distribution of body parts and shapes. They are also found at the ocean bottom, so there are no land versions of echinoderms. Besides sea cucumbers and sea lilies, other examples of echinoderms include sea stars, urchins and sand dollars.
You would need to introduce a list. For example you could have: My shopping list contains of; milk, bread, and yogurt. Another purpose is to separate clauses.
