Answer:
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.
I am mother and father, but never birth or nurse. I'm rarely still, but I never wander.
White bird, featherless, flying out of paradise. Flying over sea and land. Dying in my hand.
What letter comes next: O T T F F S S ?
A harvest sown and reaped on the same day in an unplowed field. Which increases without growing, remains whole though it is eaten within and without. Is useless and yet the staple of nations.
A doctor might remove one from the neck of a Dracula victim.