HTS heading 0307

Molluscs, whether in shell or not, live, fresh, chilled, frozen, dried, salted or in brine; smoked molluscs, whether in shell or not, whether or not cooked before or during the smoking process — 67 codes under this heading, with the duty on each.

38 of these lines state no rate of their own and inherit one from the line above, which is how the schedule is read. Each says which line it came from.

Source: Harmonized Tariff Schedule of the United States, U.S. International Trade Commission (public domain). Classification and the duties that finally apply to a shipment are a licensed customs broker's call.