horse teeth, enamel and dentin layers are intertwined, which increases the strength and decreases the wear rate of the teeth. Contrary to popular belief, horse teeth do not "grow" indefinitely. Rather, existing tooth erupts from below the gumline. Horses start to "run out" of erupting tooth in their early 30s and in the rare case they live long enough, the roots of their teeth will fall out completely in the middle to latter part of their third decade.

In manatees,