'Millstone' in the Bible

a woman threw an upper millstone down on his head and shattered his skull.

Who struck down Abimelech the son of Jerub-Besheth? Didn't a woman throw an upper millstone down on him from the wall so that he died in Thebez? Why did you go so close to the wall?' just say to him, 'Your servant Uriah the Hittite is also dead.'"

then let my wife turn the millstone for another man, and may other men have sexual relations with her.

Its heart is hard as rock, hard as a lower millstone.