Irish moss  is a tufted seaweed with thin branching fanlike fronds from 5 to 25 cm (2 to 10 inches) long. The Irish moss is cartilaginous, varying in colour from a greenish yellow to a dark purple; 

The morphology is highly variable, especially the broadness of the thalli. 

When washed and sun-dried for preservation, it has a yellowish, translucent, horn-like aspect and consistency.. 

This red sea moss is an industrial source of carrageenan, which is commonly used as a thickener and stabilizer in milk products such as ice cream  and processed foods, including lunch meat.  It is boiled in milk and strained, before sugar and other flavourings such as vanilla, cinnamon, brandy or whiskey are added.