Final answer:
Brachiopods have a shell composed of two unique valves with several layers, and a body wall consisting of an epidermis, connective tissue, and muscles. Their symmetry and the presence of a pedicle distinguish them from bivalves.
Step-by-step explanation:
Brachiopods are shelled marine organisms possessing a hard shell composed of two valves: the brachial valve and the pedicle valve. The shell layers of a brachiopod typically consist of the periostracum (outermost layer), the prismatic layer (middle layer), and the lamellar layer (innermost layer). The body wall layers of brachiopods include the outer epidermis, connective tissue, and inner muscular layers that facilitate movement of the valves. The distinctly shaped valves with their symmetrical features help differentiate brachiopods from bivalves. Moreover, the presence of a pedicle used for attachment to the seafloor is a unique feature characteristic to brachiopods.