Nori is made by shredding seaweed and pressing it into thin sheets that are toasted to dry them out. You can find nori at any Asian grocery or health-food store, and more supermarkets are starting to carry it. It will keep for months in your pantry. Look for the plain variety.
This website provides approximate nutrition information for convenience and as a courtesy only. Nutrition data is gathered primarily from the Spoonacular Database, whenever available, or otherwise other online calculators.