The Ratatorsk is a rodent about 20 cm in length plus 10 cm long tail. They are most often brown, or dark brown in color.
In nature the Ratatorsk live in swarms of 10-20 individuals. Usually in a dead tree that they hollow out.
The Ratators is a surprisingly intelligent for a creature of it's size. It is very easy to train it. It can even learn to understand simple speech. It also has a long memory. All of these traits make it an ideal spy.