Lobster is not classified as a mollusk but rather a crustacean. It is classified as an aquatic arthropod along with crabs, barnacles, and shrimp. One of the defining characteristics of these aquatic organisms is the segmented body along with a chitinous exoskeleton and jointed limbs.
Mollusks and crustaceans differ in a number of ways, including the family they are from as well as a variety of physical defining characteristics. Snails are one of the most common types of mollusks along with many others that are used for culinary purposes. Although snails are usually associated with French cuisine, they are popular in different parts of the world as well.