A colour-changing tea pet is glazed with a thermochromic pigment that shifts tone above roughly 40 °C. Pour hot water from the pot over it and the colour changes; it reverts as it cools. Each cycle is reversible but the pigment does slowly lose range with repeated high-heat exposure, so the piece is best rinsed with the water you would pour over any pet — hot, but not boiling.
Made in Dehua, Fujian, the porcelain centre that has supplied white-bodied ceramics since the Ming dynasty. Glazed inside and out; the base is left unglazed so the maker can mark it.