Sea cucumbers are football shaped creatures that lay on their side at the bottom of the ocean. They have five rows of tube feet running lengthwise. Its mouth is surrounded by tentacles that are really tubed feet. Unlike sea stars, the vascular system is not filled with sea water. Instead, sea cucumbers use a special body fluid.
Sea stars (group name Stelleroidea) are sometimes called starfish, though they are not real fish (they lack both vertebrae and fins). There are two sub-types of sea stars: Asteroideas are the true sea stars and sun stars. Ophiuroideas are brittle stars and basket stars.
Sea urchins, heart urchins, cake urchins, and sand dollars belong to a sub-group of echinoderms called enchinoidea. These creatures have many sharp spines pointing out in all directions that offer protection from predators.
Rosy Acorn Worm is a new species of acorn worm discovered some 8,850 feet (2,700 meters) deep near the Mid-Atlantic Ridge. Deepwater worms have extremely long 'lips', helping them snag prey in a place where food is scarce. via nationalgeographic