means Nori is the dark green or purplish dried seaweed, pressed into thin sheets, used to wrap sushi and onigiri or crumbled over rice and noodles.

from A Japanese word (海苔, nori), where 苔 once broadly meant mossy or slimy water-growths — the same sense of green stuff clinging to wet rock. The sheet form we know today is a relatively modern craft, made by spreading the gathered algae thin and drying it on frames, much as paper is made. The word rode into English on the same wave as sushi, keeping its Japanese shape intact.