Bladderwrack, aka Fucus Vesiculosus, is a type of brown seaweed that's harvested from cool waters along the Atlantic Ocean. It's distinguished by its air-filled "bladders" that keep it floating. This seaweed has an unusually high natural iodine content that many enjoy for its nutritious value. Bladderwrack can easily be added to soups, stocks, or broths; you can even steep it as a tea.