What is a small, purplish, branching, cartilaginous seaweed (Chondrus crispus), which, when bleached, is the Irish moss of commerce. [Also written carragheen, carageen.] called?

carrageen — A small, purplish, branching, cartilaginous seaweed (Chondrus crispus), which, when bleached, is the Irish moss of commerce. [Also written carragheen, carageen.]. (Webster's 1913.)