These clams are rarely sold by the name “hardshell” or “quahog,” but instead are sold by names reflecting size (1 1/2 to 5 inches), from  littlenecks to cherrystones, topnecks and chowders. On the West Coast, Manila clams and Washington steamer clams are sometimes called littlenecks, though they aren’t in this hardshell family.  Hardshells are the most valuable U.S. clam species, sold mostly live in bags. The clams are slow growers. Littlenecks — the most tender, most expensive and most sought-after — are 2 to 3 years old. Cherry-stones are 5 to 6 years old. Large chowder clams can be 30 years old. Hardshells are found from the Canadian Maritimes to the Gulf of Mexico in bays, coves and salty estuaries. The major U.S. harvest is taken between Massachusetts and Florida. The clams are harvested by scissors-like tongs with wire-mesh bottoms and by hand rakes and hydraulic dredges. They are also farm-raised along the East Coast.