Porphyra umbilicalis

Porphyra umbilicalis, commonly called "laver", is a species of edible seaweed in the genus Porphyra used to make laverbread. The seaweed is commonly found around the west coast of Great Britain and east coast of Ireland along the Irish Sea, where it is also known as "sleabhac" or "slake". It is smooth in texture and forms delicate, sheetlike thalli, often clinging to rocks. Porphyra is classified as red algae; it tends to be a brownish colour, but boils down to a dark green pulp when prepared. It is unusual amongst seaweeds because the fronds are only one cell thick.