Answer:
A shimmering field that reaches far. Yet it has no tracks, And is crossed without paths.
What is eaten but not grown and was born in water but will disappear if soaked?
My teeth are sharp, my back is straight, to cut things up it is my fate.
I work when I play and play when I work.
A dagger thrust at my own heart, dictates the way I'm swayed. Left I stand, and right I yield, to the twisting of the blade.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?