A pyramidic lead ’standing weight’ of polygonal (hexagonal?) cross-section, originally with an integral pierced lug at the apex, of which only the stumps remain. At a recorded value of 29.9g, the weight is probably a trade weight with a denomination of one ounce.
The dating of lead weights of this general type is very problematic. They are plausibly late medieval, and Norman Biggs illustrates a group of similar examples in English Weights, which he suggests are "probably 12th-13th century". Lead, however, continued to be the metal most frequently used for trade weights until the end of the 17th century, and its use was not actually banned until 1834.
From about the beginning of the 15th century, the legal requirements for trade weights to be officially verified became progressively more rigorous, and unmarked weights of later periods would not officially have been acceptable. Those that were verified can usually be dated, and from the 16th century onwards they are invariably flat (circular or shield-shaped), rather than of the standing weight form. Although unofficial weights will undoubtedly have continued in use for a very long time, it would seem unlikely that their form was conspicuously different to that of their official counterparts, as it would merely draw attention to their questionable status. The tentative dating shown below relies to a large extent on this argument.