Answer:
I have an eye but cannot see, You'll head inside when you see me.
This thing all things devours: Birds, beasts, trees, flowers; Gnaws iron, bites steel; Grinds hard stones to meal; Slays king, ruins town, And beats high mountains down.
Three lives have I. Gentle enough to soothe the skin. Light enough to caress the sky. Hard enough to crack rocks.
Three little letters. A paradox to some. The worse that it is, the better it becomes.
My prefix is food. My suffix is rude. My infix comes in rounds. I keep you off the ground. What Am I?
What age most travelers have?