Tri-color glazed cup in duck design

Any idea what this tri-color glazed duck-shaped artifact is used for? It’s a cup from the Tang Dynasty (618-907). The duck turns its head back with its beak holding its lotus leaf-shaped tail, which serves as the cup’s rim. This piece exudes graceful and delicate beauty with its soft and harmonious colors.

Unearthed in Anxin county, Baoding, Hebei, the cup is now housed by the Hebei Museum.