One fine day in the middle of the night
Two dead men got up to fight
Back to back they faced each other
Drew their swords and shot each other!
What is wrong with this?
Day to night, dead men cannot fight, back to back how could they face each other, swords don’t shoot.
Rough and gray as rock,
I'm plain as plain can be.
But hidden deep inside there's great beauty in me.
What am I?