The document discusses different classes of mollusks. It begins by explaining that mollusks are soft-bodied invertebrates usually with shells. They are found on land, in water, and salt water. The three main classes are gastropods which include snails and slugs, bivalves like clams and oysters, and cephalopods such as squid and octopuses. Each class has distinct physical traits and ways of living.

12. Cephalopods

13. Firefly Squid