Why is this statement false the hard spiny skin of an echinoderm is called an exoskeleton?

The statement is false because the hard spiny skin of echinoderms, such as sea stars and sea urchins, is not classified as an exoskeleton. Instead, it is known as a "test" or "ossicle" structure made of calcium carbonate plates that form a rigid internal support system. Echinoderms possess an endoskeleton, meaning their skeletal structure is located inside their body rather than on the outside, as is the case with true exoskeletons found in organisms like insects and crustaceans.