In June 2016, J. K. Rowling revealed on Pottermore that Slytherin's wand contained a fragment of basilisk horn, and was taught by its creator to "sleep" when instructed, which meant that it could place others who possessed the wand in a sleep from which they could only be awakened by the cries of the person's children. This secret was handed down through the centuries to each member of Slytherin's family who possessed it. By the 1600s it belonged to the Irish witch Gormlaith Gaunt, though in about 1620 it was stolen by her then-17-year-old niece Isolt Sayre, who fled to Massachusetts in the United States, where she founded the Ilvermorny School of Witchcraft and Wizardry. She buried the wand outside the school grounds, and within a year, an unknown species of snakewood tree grew from the burial spot. It resisted all attempts to prune or kill it, but after several years the leaves were found to contain powerful medicinal properties.