What it is
Sea vegetables that have anchored coastal diets for millennia — nori around sushi, wakame in miso soup, dulse off the Atlantic rocks.
Why your biology objects
Whole sea vegetables supply iodine for thyroid hormones, plus minerals and carotenoids, in the form coastal ancestors ate. Nori and wakame sit at the modest, everyday end of the iodine range — the safe default. (Kelp is the high-iodine outlier; see its line.)