I have a heart of stone and a body of wood. I eat grain but never swallow. What am I?

Q: I have a heart of stone and a body of wood. I eat grain but never swallow. What am I?

A windmill (or watermill).. The stone is the millstone; the wooden body is the housing; the grain enters but only its flour leaves — the mill never ‘swallows.’

Question

Accepted Answer

A windmill (or watermill). — The stone is the millstone; the wooden body is the housing; the grain enters but only its flour leaves — the mill never ‘swallows.’