Chonrus crispus, known under the common name Irish moss, or carrageen moss (Irish carraigín, "little rock"), is a species of red alga which grows abundantly along the rocky parts of the Atlantic coast of Europe and North America. In its fresh condition the plant is soft and cartilaginous, varying in colour from a greenish-yellow, through red, to a dark purple or purplish-brown. The principal constituent of Irish moss is a mucilaginous body, made of the polysaccharide carrageenan of which it contains about 55%; the plant also has nearly 10% of protein and about 15% of mineral matter, and is rich in iodine and sulfur. When softened in water it has a sea-like odour, and because of the abundant cell wall polysaccharides it will form a jelly when boiled, containing from 20 to 100 times its weight of water.