The black line on the outer ring of razor clams, the black part inside the meat of razor clams and the shell of razor clams.

After blanching razor clams, the shells will be separated from the meat, and there is a narrow circle of black film on the outside of the meat, which is almost detached from the meat, so you can just peel it off.

Razor clam (Latin name: Sinonovacula constricta (Lamarck)), is the curtain clam order (Veneroida) bamboo razor clams family (Solenidae) Valvularia mollusks of the common name, also known as razor clam emperor, the holy son, bamboo locusts, dragon. The shell is long, nearly columnar or ovoid, and the two shells are equal. China's abundance of razor clams, the north and south coasts have a lot of distribution.

Razor clam meat can be eaten fresh, can also be processed into dried razor clams, razor clam oil. China has a long history of culture, with the largest production in Fujian and Zhejiang, and artificial culture.