bells (idiophones) <p>Percussion vessels consisting of a hollow object, usually of metal but in some cultures of hard clay, wood, or glass, which when struck emits a sound by the vibration of most of its mass; they are held in position at their vertex, the point farthest from their rim, and their zone of maximum vibration is towards the rim.</p> <p>Source: Art &amp; Architecture Thesaurus</p> <p>http://vocab.getty.edu/page/aat/300041872</p>