Noodles are a staple food in many cultures made from unleavened dough which is stretched, extruded, or rolled flat and cut into one of a variety of shapes. A single noodle can be made, eaten, or extracted from a serving of noodles, but it is far more common to serve and eat many at once, and thus more common to see the plural form of the word. While long, thin strips may be the most common, many varieties of noodles are cut into waves, helices, tubes, strings, or shells, or folded over, or cut into other shapes. Noodles are usually cooked in boiling water, sometimes with cooking oil or salt added. They are often pan-fried or deep-fried. Noodles are often served with an accompanying sauce or in a soup. Noodles can be refrigerated for short-term storage, or dried and stored for future use. The material composition or geocultural origin must be specified when discussing noodles. The word derives from the German word Nudel. The origin of noodles has been disputed, but the evidence heavily favors its origin in China. Claims have been made that the noodle was of Chinese, Arabian and Mediterranean origin. Given the scarcity of physical evidence, it is unlikely that the question of origin can even be answered with certainty. A Nature article claimed the oldest evidence of noodle consumption was from 4,000 years ago in China. In 2005, a team of archaeologists working in the Peoples Republic of China reported finding an earthenware bowl that contained foxtail millet and broomcorn millet noodles at the Lajia archaeological site, arguably hailing from the late neolithic period, but this claim was disputed by later research, which suggested that noodles simply cannot be produced from millet, which lacks gluten.