A tooth is part of most animal's anatomy. Teeth are a calcified, whitish structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of multiple tissues of varying density and hardness. The cellular tissues that ultimately become teeth originate from the embryonic germ layer, the ectoderm.
When the Balunians landed and Wonder Dog first saw them, he was frightened by them because he saw Krim grow to human size. He then got back in his doghouse, hiding in terror, and you could here the sound of him chattering his teeth.