Humans have utilized snails since prehistoric times, although today some fast reproducing and introduced species can be considered pests. An early source of food, in some parts of the world snails, or escargot, continue to be considered a delicacy. In addition to their edibility, snails have been prized solely for their shells, which have been used by various societies throughout history as jewelry, as decorations, as a form of commercial exchange, and even as a badge of office. Perhaps snails are most important, however, for their integral role in the decomposition of plants and animals, which are modified into substances that can support new life.