The answer is sea stars. Sea stars can then push their stomachs out of the body while inserting it into the prey thus the food is being digested externally. Echinoderms are having 5 or at times multiple of 5 arms. Their shell is made of calcium carbonate.
B. Independent meaning by itself. Dependent meaning together, or not by itself, and since both are going 60mph and they both stop it’s dependent because they’re depending on each other to stop.