Mastrocarpus stellatus is a red seaweed that is often found on rocky coastlines in the North Atlantic. In taxonomic terms, this seaweed belongs to the Kingdom Plantae, the Phylum Rhodophyta, the Class Florideophyceae, the Order Gigartinales, the Family Phyllophoraceae, the Genus Mastrocarpus and the Species Mastrocarpus stellatus. In terms of morphology, this seaweed has a reddish color with cartilaginous blades, which allow its attachment to rocks. It grows from a discoid stipe up to 10-20 cm. M. stellatus is used in the food and pharmaceutical industries due to the presence of polysaccharides, specifically carrageenan. This is a gelatinous substance used to make jellies, yogurts, among others.