Irish sea moss (chondrus crispus) aka carrageenan
Irish sea moss carpets many of the intertidal ledges along the coast, and was historically harvested with bronze rakes from small wooden boats, or plucked by hand from the rocks while wading in shallow tide pools. It releases a powerful gelling agent when boiled, commonly known as “Carageenan,” a word originating from the Irish name for the plant. The plants can contain up to 50 % carageenan by weight, and a small handful can easily thicken a quart of liquid to a jello-like consistency. It has historically been used to “set” puddings, custards, and ice creams, and also serves as an excellent thickening agent in savory soups and broths.
In addition to the full complement of trace minerals found in all seaweeds, moss contains unique anti-viral properties, and has been used internally to treat coughs and chest infections. The gel can also be used topically in skin-care applications.
Sea moss often contains small periwinkle shells, krill (tiny crustaceans), and other foreign matter, so thorough rinsing is usually necessary.
Irish Moss Custard
Rehydrate a “scant handful” of moss in several changes of fresh water to mellow the flavor and reduce saltiness. Meanwhile, heat 1-2 quarts of milk or cream to a simmer and add the moss, along with a few tablespoons of maple syrup, sugar, or other sweetener to taste. Blend in a handful of fresh or frozen berries at this stage if desired. Leave to steep off the heat for 20 minutes, then strain. Chill in a serving bowl until set, and serve with fresh berries.