Dulse

Palmaria palmata, also called dulse, dillisk or dilsk , red dulse, sea lettuce flakes, or creathnach, is a red alga (Rhodophyta) previously referred to as Rhodymenia palmata. It grows on the northern coasts of the Atlantic and Pacific Oceans. It is a well-known snack food. In Iceland, where it is known as söl [ˈsœːl̥], it has been an important source of dietary fiber throughout the centuries. The earliest record of this species is on the island of Iona, Scotland where Christian monks harvested it over 1,400 years ago.

Source: Wikipedia