Freshly foraged on the low tide at Helford I found some nice Sugar Kelp which is the one in the background has large wavy edge leaves also called Kombu in Japanese dishes), which contains a good amount of vitamin C and is high in iodine, protein and calcium.
The Oarweed also called Tangle weed as it tends to tangle itself in the oars of boats! It can also be foraged on a fresh tide for stews and soups. High in nutrients and trace elements, yummy. Can grow up to 10 feet.