One of the two primordial ancestors of the Tao, born when the sky god cast a stone onto the peak of the island's central mountain and a man emerged from it. In the widely recorded version his knees later swelled and split, and from them issued children who, together with the offspring of the bamboo-born ancestor, became the progenitors of humankind. The narrative explains the origin of the marriage rule: children sprung from a single ancestor's knees who married one another produced blind or malformed offspring, whereas unions across the two ancestral lines produced whole and healthy descendants. The stone-born ancestor's personal name is not preserved in the texts, which identify him by his miraculous origin.