A mollusk with a spiral shell is commonly referred to as a SNAIL. Snails are gastropod mollusks, meaning they have a single, muscular foot and a shell that is coiled in a spiral shape. They are found in a variety of habitats, from freshwater to marine environments, and can range in size from a few millimeters to over 30 centimeters. Snails are known for their slow movement, but they are also capable of retracting into their shells for protection.