Answer:
When it was young, it had a tail. When it grew up, it had knees
What has armor but is not a knight, snaps but is not a twig, and is always at home even on the move?
A spent round or a slimy critter.
Though desert men once called me God, today men call me mad. For I wag my tail when I am angry. And growl when I am glad.
They are producers of pies and burgers and are great for tipping.
What is always coming but never arrives?