Although this species is also known as ‘sea spaghetti’, I prefer thongweed because it brings those sea nymphs to mind. Thongweed forms dense populations that look like very coarse hair draped over the rocks at low tide. The long fronds are branched and 61 ⁄2ft long. They grow from mushroom-shaped structures of about 1in in diameter that are attached to the rocks. These ‘mushrooms’ are very often found on their own, causing confusion to those new to phycology. Thongweed is edible.