Nori is often used for Japanese food. For example, it is used for Onigiri, rolled sushi, Gunkanmaki of sushi and so on.  Nori is made by stretching the seaweed into a paper and then drying it.

Nori, 海苔

In addition, many Westerners do not have enzymes that digest seaweed. So they eat it but they are discharged without being digested.