*Tribbles are small, fluffy creatures, ranging in length from three to fourteen inches. Tribbles are extremely simple creatures, exhibiting a purring when in contact with a sympathetic warm body. The trilling they produce has a calming effect upon the Human nervous system. While Tribbles are not harmful, they do reproduce at an alarming rate, Tribbles have a reciporcal aversion to the Klingon race; they react with a loud screeching whenever Klingons are in close proximity. *Source: Back of card