A manikin, or elf, secretly substituted for a young child.
There are many tales of such occurrences in Scotland. The
changeling grows up peevish and misshapen, always crying,
and gives many proofs of its origin to those versed in such matters.
There were many ways of getting rid of him, such as sticking
a knife into him, making him sit on a gridiron with a fire
below, dropping him into a river, and so on. The changeling
sometimes gave himself away by reference to his age. (See also
McNeil, F. Marion. The Silver Bough. Vol. 1, Scottish Folklore
and Folk-Belief. Glasgow, Scotland William Maclellan, 1957