We got Marisa R. to answer this question. However, we assumed that you meant Belly Buttons.
Not only people have belly bottons... cats and dogs, pigs and cows, lions and elephants do too. They all are mammals.
In mammals, babies do not hatch from eggs, they develop inside their mother's womb. While in the womb, the fetus (which is the developing baby) gets its nourishment from the mother through the umbelical cord (a sort of pipe which allows the blood of the mother, rich in nourishment, to reach the developing baby).
As soon as the baby is born the ombelical cord is cut. The little piece left on the baby's belly will dry out and fall off a few days later and the scar left is the belly botton.
Ask your mom or your dad about it. They will be able to tell you when your belly botton first appeared.% % filename IO.DOT
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