A similar prank played by many faeries is the exchange of a changeling for a human child. The faerie child appears the same as the human one, but has a large appetite, is mischievous, malicious and may have some deformity. The best way to prevent the faeries from replacing a baby with a changling is to put a bible, piece of iron , red thread or ash berries in the cradle. For all of these are wards against faeries. If a child is thought to be a changling, then the best way to get your child back is to startle the changling into revealing its true name. For instance one wife from Brittany boiled milk in eggshells, and the startled changling blurted out "I shall soon be a hundred years old, but I never saw so many shells boiling! I was born in Pif and in Paf, in the country where the cats are made, and I never saw anything like it!" Sometimes the amazement of the changling is enough to make him depart, but more often once his identity is proved he must be thrown on the fire or in the river to get rid of him. He will cry out and his elfin parents will rescue him, bringing the lost human bay back as well.
Many faeries use their shape-changing abilities to play tricks on mortals. The Chevel Bayard often takes the form of a horse and when humans ride him, he throws them into the bushes. the Phooka plays similar tricks, but takes a wider range of animal forms. The kelpie also uses the horse ruse, as well as that of a beautiful maiden to lure men into the water with it, where it drowns them.
Faeries also torment humans indirectly by causeing all sorts of household mischief, like breaking or spilling objects, causing chores to take twice as long, and harming or stealing livestock. Many of the problems with animals are blamed on the little people, including sudden illnesses and deaths. Wounds would be blamed on elf shot, and even if no wound could be found the shot might have caused a strange paralysis. To this day the term stroke is often used to describe a paralytic seizure, but originally came from the expression 'elf-stroke'