Cotton, hemp, jute, flax, abaca, pina, ramie, sisal, bagasse, and banana are all examples of vegetable fibers based on cellulose groupings, frequently with lignin. Plant fibers are used to make paper and textiles (cloth), and dietary fiber is an essential part of human nutrition. Animal hair such as sheep's wool and alpaca fur, along with bone, cartilage, and feather are all derived from biological materials that consist mainly of collagen. These too are called natural fibers. There are several other materials used in manufacturing that are not classified as food or fuel but do contain large amounts of oxygen: iron ore, copper ore, silver ore, zinc ore, and lime. These substances are important ingredients in cement, bricks, glass, ceramics, and chemicals. Fibers are used in a wide variety of products including clothing, paper, carpeting, sporting goods, and industrial fabrics. The word "fiber" is used to describe the long strands found inside plants and animals that are responsible for their strength and resilience. Fiber comes in three main types: cellulose, which makes up most plant material; protein, which is present in animal tissue; and oil, which is found in seeds. Natural fibers are usually more sustainable than synthetic fibers because they are biodegradable or recyclable.