Purple clay, is the principle clay, which turns red-brown or dark-brown after firing. The artisan often adds iron clay to achieve a better color effect.
Red clay, also known as “Stock Yellow”, has a much higher contraction percentage than purple clay, and shows a vermillion color after firing. Because of its high contraction percentage, red clay is more suitable for making small-sized objects like tea pets and teapots.
Green clay has a color similar to duck egg shell, and appears off-white after firing. It is rarer than purple clay, and more expensive on the market." -Wikipedia
"A tea pet, also known as a tea lover's pet, is a small clay figure which is kept by some tea drinkers for good luck. The history of tea pets can be traced back to the Yuan dynasty (1206–1368). They are usually made of "zisha" or Yixing clay, from the region near Yixing in Jiangsu province, China. Just like Yixing teapots made of the same clay, tea pets are unglazed, so that they are mostly monochromatic with a rough surface. Tea lovers in China raise a tea pet by placing it on the tea tray during tea time and pouring out the tea over it. The most popular figure of the tea pet is the “pee-pee boy”, which is used to judge whether the water is hot enough to make tea. Tea pets are also molded into zodiac animals or Chinese mythical creatures such as dragons, Pixiu, Qilin, etc., to symbolize good luck, fortune and happiness, as well as historical or mythical characters such as Guanyin, Maitreya and Zhu Geliang." https://en.wikipedia.org/wiki/Tea_pet