Nori refers to the paper-like sheets of dried seaweed, which is often cultivated. For many people outside of Japan, it might look like carbon paper, but it is an indispensable part of Japanese cuisine. Nori is usually sold in 25 centimetre squares. Ten billion sheets of nori are produced annually. It complements the staple of rice. It is commonly used to wrap up onigiri rice balls, which often appear in a Japanese lunchbox, and to wrap up sushi.