Answer:
Canine children.
I am needed for most animals and hardcover books. What am I?
kings and queens may cling to power and the jesters may have their call. I am the most common but I can rule them all.
I have roots nobody sees. I am taller than trees. Up up I go but I never grow.
What gets bigger when more is taken away?
What did the piece of wood say when he saw the screwdriver and screws approaching?
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic