Thematic Bible: Natural rocks sometimes used as

And Gideon went in and made ready a kid and unleavened cakes of an ephah of flour; the flesh he put in a basket, and he put the broth in a pot and brought it out unto him under the oak and presented it. And the angel of God said unto him, Take the flesh and the unleavened cakes and lay them upon this rock and pour out the broth. And he did so. Then the angel of the LORD put forth the end of the staff that was in his hand and touched the flesh and the unleavened cakes; and there rose up fire out of the rock and consumed the flesh and the unleavened cakes. Then the angel of the LORD departed out of his sight.

So Manoah took a kid with a present and sacrificed it upon a rock unto the LORD, and the angel did wondrously, and Manoah and his wife looked on. For it came to pass, when the flame went up toward heaven from off the altar, that the angel of the LORD ascended in the flame of the altar as Manoah and his wife looked on, and they prostrated themselves on the ground on their faces.