An oak-apple is a spongy, brightly colored gall found on the
leaf bud of oak trees; it is globular in shape. In folklore, oakapples
could be used in divination. To discover whether a child
was bewitched, three oak-apples were dropped into a basin of
water under the child’s cradle, at the same time preserving the
strictest silence. If the oak-apples floated, the child was not fascinated,
but if they sank, the child was believed to be bewitched.