Ulva lactuca is a thin flat green strain of macroalgae. The margin is somewhat ruffled and often torn. It may reach 18 cm or more in length, and up to 30 cm across. The membrane is soft and translucent, and grows attached to rock by a small disc-shaped holdfast.

Ulva can be eaten in salads or used in soups. Ulva is a particularly popular food in Scotland. Dried Ulva lactuca is made up of 15% protein, 50% sugar and starch, less than 1% fat, and 11% water. It is useful as roughage in the human digestive system. Ulva is very high in iron, as well as protein, iodine, aluminum, manganese and nickel. It contains vitamin A, vitamin B1, vitamin C, sodium, potassium, magnesium, calcium, soluble nitrogen, phosphorous, chloride, silicon, rubidium, strontium, barium, radium, cobalt, boron and trace elements.