Cellulose is a long-chain polymeric polysaccharide carbohydrate, of beta-glucose. It forms the primary structural component of green plants. The primary cell wall of green plants is made primarily of cellulose; the secondary wall contains cellulose with variable amounts of lignin. Lignin and cellulose, considered together, are termed lingo cellulose, which (as wood) is argued to be one of the most common biopolymers on Earth (chrysolaminarin is often argued to be the other). Only one group of animals, the tunicates, has the ability to create and use cellulose. Some acetic acid bacteria are also known to synthesize cellulose.