The Wonderful Rock
One day, a korrigan girl will have a child and she ask for a nurse to help her.
When the bay was born, the kirrigan said to the nurse to rub the child's eyes with a little rock wich is inthe cupboard. Intrigued, the nurse asked himself what is his rock, what are its properties. An to known the answer, the nurse rubed her right eyes with the rock.
In fact, the rock allow human to see korrigan when they are invisibled.
Some days after, the nurse saw the korrigan taking pieces of tissue without paying. In the evening, she met the korigan on the road and she asked for explanations. The korrigan answered the question and plucked the nurse's right eye and the nurse never saw again a korrigan when they were invisibled.