The king is come unto his hall Under the Mountain dark and tall. The Worm of Dread is slain and dead, And… — J. R. R. Tolkien

It cannot be seen, cannot be felt,

Cannot be heard, cannot be smelt.

It lies behind stars and under hills,

And empty holes it fills.

It comes first and follows after,

Ends life, kills laughter.

To say that Bilbo's breath was taken away is no description at all. There are no words left to express his staggerment, since Men changed the language that they learned of elves in the days when all the world was wonderful.

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 mountain down.