Seaweed is an alien–like plant that lives under the sea for its entire life. Somehow, Japan eventually developed a way to mash seaweed into a paper-like product which works as an excellent vehicle for rice and fish (the primary components of sushi).
Seaweed tastes mediocre to bad. After it’s mashed into the popular paper–like format, it’s generally used as a vehicle and structural element to sushi. Seaweed that isn’t made into the paper–format (sometimes referred to as “nori”) is terrible.
Seaweed became an official snack on May 30th 2012.