added by archaeologs A type of medieval pottery flask, of which the majority were made of leather and have not survived. Merovingian and Carolingian pottery costrels tend to be roughly round in shape, with a slight neck for a stopper. The best-known is the Zelzate costrel, made in the 'Badorf-type' industries of the central Rhineland, which contained a Viking-period hoard dating to 870.