Echinoderms generally have endoskeletons.
a. true
b. false

True.

Explanation:

Echinoderms are invertebrates that lacks the notochords and other well defined structures present in vertebrates. Echinoderms are generally marine, aquatic animals.

The skeleton of echinoderms are endoskeleton. They endoskeleton is made up of calcium carbonates interlocking in the form of plates and spines. The skeleton of echinoderm are covered by epidermis.

Thus, the answer is true.