This is the largest specimen known so far of a popular Islamic glass form – the pear-shaped ewer with almond-shaped mouth. The shape can be traced back to Sasanian glass ewers, and the longevity of this Sasanian tradition is attested by Abbasid specimens that have been found at Samarra, in contexts generally dated to the ninth or tenth century; and by the cut-glass or rock-crystal ewers of the late eighth–eleventh centuries, of which perhaps the best known is the rock-crystal ewer inscribed in the name of the Fatimid caliph al-'Aziz (r.365–386 AH / AD 975–AD 996) in the treasury of San Marco in Venice. The form spread to the Byzantine world, as is shown by one complete and one fragmentary example from the Serçe Limani wreck. The pyriform body of this ewer stands proudly undecorated, while its narrow neck has been festooned with an applied thick tread.