Pet rock in the context of "Novelty item"

A novelty item is an object which is specifically designed to serve no practical purpose, and is sold for its uniqueness, humor, or simply as something new (hence "novelty", or newness). The term also applies to practical items with fanciful or nonfunctional additions, such as novelty aprons, slippers, or toilet paper. The term is normally applied to small objects, and is generally not used to describe larger items such as roadside attractions. Items may have an advertising or promotional purpose, or be a souvenir.