For 10 points, name this phylum of spiny skinned invertebrates that includes sea cucumbers and sea urchins.
One member of this phylum is Arbacia punctulata, a model organism commonly studied by developmental biologists because its eggs are transparent. Some members of this phylum can chew through stone with an organ known as "Aristotle's lantern," and members of this phylum have skeletons formed of calcite ossicles. The ampulla and podia make up their (*) tube feet, which, along with the madreporite, are a component of their water vascular system. These deuterostomes exhibit bilateral symmetry in their larvae, in contrast to their radially symmetric adult forms. For 10 points, name this phylum of spiny skinned invertebrates that includes sea cucumbers and sea urchins.
One member of this phylum is Arbacia punctulata, a model organism commonly studied by developmental biologists because its eggs are transparent.
 echinoderms or echinodermata