There are several old traditional aspects to this tea cup by an unknown maker. It is done in the majolica/ maiolica style with a white glaze over a red ware body. Early European potters employed this technique trying to copy the porcelain coming from Asia.
The proper clay to do porcelain (kaolin) wasn’t available to the Europeans and only trade with Asia brought in the desired porcelain. The other aspect of this cup is the duck figure swimming in the bottom. You can find early drinking cups with frogs, etc. in the bottom of the bowl as a joke to be revealed on emptying a full cup.