One extraordinary attribute of ulvan is the occurrence of uncommon sugars within its backbone, namely sulphated rhamnose and iduronic acid. Rhamnose is an unusual sugar, typically found in bacteria, plants and accumulate unusual in animals, and branching of O-2 of 1,4-linked ?-L-rhamnose residue was found only on an exopolysaccharide synthesised by the bacterium Arthrobacter sp. The existence of iduronic acid in the ulvan polysaccharidic chain represents another striking characteristic, as this sugar residue has never been identified in algal polysaccharides (Quemener et al. 1997; Alves et al., 2013). One extraordinary attribute of ulvan is the occurrence of uncommon sugars within its backbone, namely sulphated rhamnose and iduronic acid. Rhamnose is an unusual sugar, typically found in bacteria, plants and accumulate unusual in animals, and branching of O-2 of 1,4-linked ?-L-rhamnose residue was found only on an exopolysaccharide synthesised by the bacterium Arthrobacter sp. The existence of iduronic acid in the ulvan polysaccharidic chain represents another striking characteristic, as this sugar residue has never been identified in algal polysaccharides (Quemener et al. 1997; Alves et al., 2013). .