Minoan craftsmen were particularly skilled at the art of seal engraving. Though small, Minoan seal stones often show scenes that are both beautifully carved and an insight into this ancient culture. Seals had a practical purpose - they were used to impress a pattern onto lumps of clay around the fastenings of doors, jars, boxes, and even bundles of documents. They could indicate ownership or the identity of a controlling authority, and were part of the Minoan administrative systems that controlled movements of goods and produce. The seals were also decorative: the stones used were usually attractive, and the seals could be worn like jewellery, suspended from the wrist or neck. This example, carved in agate, shows a man leading a tethered bull. Bulls are very common in Minoan art, perhaps most famously in bull-jumping scenes. Representations of the capture and leading of bulls may represent the preliminaries to these bull sports.