The most characteristic of Viking ornaments is undoubtedly the brooch. It was usually oval in shape and the concave surface was covered with a framework of knobs and connecting bands, which divided it into a series of 'fields' (to use a heraldic term), which could themselves be decorated with the characteristic ornamentation of the period. The commonest form of oval brooch was that with nine knobs on a single plate, but in the later examples the plate is often doubled. The brooches themselves were of bronze, the knobs usually of silver with silver wire along the edge of the brooch. These knobs have now often disappeared and the bronze has become dull with verdigris, so that it is difficult to form an idea of their original magnificence. The oval brooches were used to fasten the outer mantle and were usually worn in pairs, either on the breast or on the shoulders, and examples of them have been found from Russia in the East to Ireland on the West. Other types of brooch are also found--straight-armed, trilobed and round. Such brooches were often worn in the middle of the bosom a little below the oval ones. Other ornaments beside brooches are common--arm-rings, neck-rings, pendants. One of the most interesting of the pendants is a ring with a series of small silver Thor's hammers which was probably used as a charm against ill-luck. All these ornaments alike are in silver rather than gold, and it has been said that if the post-Roman period of Scandinavian archaeology be called the age of Gold, the Viking period should be named the age of Silver. The style of ornamentation used in these articles of personal adornment as well as in objects of more general use, such as horse-trappings, is that commonly known to German archaeologists as _tier-ornamentik_, i.e. animal or zoomorphic ornamentation. This last translation may sound pedantic but it is the most accurate description of the style, for we have no attempt to represent the full form of any animal that ever had actual existence; rather we find the various limbs of animals--heads, legs, tails--woven into one another in fantastic design in order to cover a certain surface-area which requires decoration. 'The animals are ornaments and treated as such. They are stretched and curved, lengthened and shortened, refashioned, and remodelled just as the space which they must fill requires.' This style was once called the 'dragon-style,' but the term is misleading as there is no example belonging to the Viking period proper of any attempt to represent a dragon, i.e. some fantastic animal with wings. Such creatures belong to a later period.