Plant
Algae comprise several different groups of organisms which produce food by photosynthesis and thus have traditionally been included in the plant kingdom. The seaweeds range from large multicellular algae to single-celled organisms and are classified into three groups, the brown, red and green algae. There is good evidence that the brown algae evolved independently from the others, from non-photosynthetic ancestors that formed endosymbiotic relationships with red algae rather than from cyanobacteria, and they are no longer classified as plants as defined here.
Nori
Raw seaweed is 85% water, 6% protein, 5% carbohydrates, and has negligible fat (table). In a 100 gram reference amount, seaweed is a rich source (20% or more of the Daily Value, DV) of vitamin A, vitamin C, riboflavin, and folate (table). Seaweed is a moderate source (less than 20% DV) of niacin, iron, and zinc. Seaweed has a high content of iodine, providing a substantial amount in just one gram. A 2014 study reported that dried purple laver ("nori") contains vitamin B12 in sufficient quantities to meet the RDA requirement (Vitamin B12 content: 77.6 μg /100 g dry weight).