👉 Mollusca is a class of marine animals that include clams, oysters, and mussels. These creatures are divided into two main groups based on their shells: the true mollusks (those with a hard, waterproof shell) and the gastropods (those without shells). Mollusks play an important role in marine ecosystems by providing food for many other organisms that inhabit the water around them, as well as contributing to the overall health of the ecosystem.