Three Jin. Hemlock is a kind of clam, which is a kind of shellfish in the sand ditch. It belongs to Mollusca, Lamellibranchia, Dermatidae and Scapharca. It is mainly distributed in the coastal areas of China, North Korea and Japan, especially in the Bohai Sea and the East China Sea in China. One catty of clam with shell has about four or two meats, so it needs to be peeled.