Definition: In the Bible, "Annelida" refers to the group of small invertebrates that include oyster molluscs (Cnidaria), sea urchins, sea cucumbers, limpets, barnacles, and crabs. They are classified as gastropods due to their shell-like appendages, but they have a distinct cephalopod skeleton with three pairs of arms, two pairs of legs, and the head, which is often not fully defined.