The phylum Mollusca is a very diverse group that includes clams, snails,
and octopus. The groups with hard parts are found in today’s oceans,
lakes, and rivers include gastropods (snails) and bivalves (clams).
Gastropods have spiral symmetry while bivalves have two shells
that are bilaterally symmetrical.
The shells of bivalves can provide information on how the clam lived.
Many bivalves adapt to their muddy and sandy lifestyles.
Bivalve life position