A brooch used to fasten garments at the shoulder in antiquity and the Early Medieval and Byzantine periods. Often made of precious materials and highly decorated, fibulae (pl.) worked like modern safety pins. Web resource here.
A pair of fibulae. Part of the Treasure of Untersiebenbrunn, from a Gepid (East Germanic) grave. Gold-plated silver inlaid with garnets, glass, and enamel. Ca. 430 CE. Kunsthistorisches Museum, Vienna.