310 million years ago, various shell animals thrived in ancient seas, with less reliance on shells for defense than in later ages. Gastropods, including drills, periwinkles, and snails, were common, while bivalve gastropods like mussels, clams, oysters, and scallops have persisted largely unchanged. Brachiopods, with their hinged and notched valve shells, also flourished, resembling their modern forms. [1]