Changelings could be things like glamoured rocks and logs, but were also often old fairies that no one wanted to deal with anymore, and so they were given to mortals in exchange for children. There were many myths about how to get one’s loved one back from fairies when they were replaced with a changeling. One of the ways to discover if your child was a changeling in Ireland involved brewing eggshells. The changeling would be so perplexed that it would comment on the act, revealing itself to be far older than a human infant or child. Once found out, the changeling could be exchanged for the true human child.
People who have studied the phenomenon and its history have a dark tale to tell. They believe that the changeling legend was eventually used, specifically in Ireland, as an excuse for people to abuse, neglect, and even kill disabled people, as changelings were often described as being different from normal humans in many ways. However, it was also occasionally used as an excuse to kill anyone who did not quite fit in, much like the excuse of witchcraft was used in other European countries. The last recorded case of this was in 1895, when an ill woman named Bridget Cleary was murdered by her husband and several of his friends. Her corpse was found burned and brutally mutilated, and her husband refused to murder. He instead said that he had succeeded in driving the fairy out, and that his wife would soon be returned to him. He was found guilty of manslaughter and sentenced to fifteen years in prison, but this was in a much more modern age. The stories of changelings are much older than that.