Mollusca is a large and diverse group of invertebrate animals that includes snails, clams, octopuses, and squids. They are characterized by their soft bodies, which are often protected by a hard shell made of calcium carbonate. Mollusks are found in various habitats, from oceans and freshwater to terrestrial environments. Mollusca is divided into several classes, including Gastropoda (snails and slugs), Bivalvia (clams and oysters), and Cephalopoda (octopuses and squids). These animals exhibit a wide range of forms and behaviors, with some being slow-moving grazers and others being fast, agile predators.