Once upon a time, there was a little lamb named Bob. And Bob was a very good lamb. He was fluffy and snow white with a miraculous ability to always be clean. He huffed and puff his fat little self to ever nice patch of green, chomping away without any fear of wolves or other predators.
This was because they all fell in awe of his white fluff. So he lived a charmed life and, of course, he never aged. He just continued to be puffy and cute, shoving his black face into every fresh patch of grass. And the grass was eternal. He could eat forever.