This is an example of a ball-type penannular brooch, which would have functioned as a dress or cloak fastener. The type originated in the native Irish tradition during the second half of the ninth century. Its fabrication in silver was made possible for the large quantities of this precious metal into Ireland by the Vikings. Early examples of ball-type brooches, such as this one, exhibit solid globular terminals with criss-cross brambled decoration and are consequently often referred to as thistle brooch. They occur quite commonly as single finds in Ireland, particularly in the midlands and the south, such as the one that was found with the famous chalice at Ardagh, county Limerick.