nori

This just might be the sea vegetable you know best since it's typically used to make sushi rolls like California Rolls. Look for nori to be dark purple to marine green. It's readily available toasted or untoasted, too. Eat up; it contains both iodine and vitamin C so don't hesitate to use it as a condiment for rice, soups, salads, casseroles or grains either crushed into flakes or cut into strips.