Saturn is the one who has the fire to ignite a new cycle and newborn babies are wet (whereas old people are dry). In order to release a new 'land' the old one has to be sacrificed, cfr the myth about the death of Ulu in chapter 16. And the top of the head was the only part visible of the Hawaiian war god Ku after his sacrifice:

... the breadfruit originated from the sacrifice of the war god Ku. After deciding to live secretly among mortals as a farmer, Ku married and had children. He and his family lived happily until a famine seized their island. When he could no longer bear to watch his children suffer, Ku told his wife that he could deliver them from starvation, but to do so he would have to leave them.

Reluctantly, she agreed, and at her word, Ku descended into the ground right where he had stood until only the top of his head was visible. His family waited around the spot he had last been, day and night watering it with their tears until suddenly a small green shoot appeared where Ku had stood. Quickly, the shoot grew into a tall and leafy tree that was laden with heavy breadfruits that Ku's family and neighbours gratefully ate, joyfully saved from starvation ...

Tears are drops of water and without them nothing will sprout. Thus there must be a sacrifice. First the dry old 'calabash' has to be buried in the earth and then there must be 'tears'. First comes the fall and then the 'water of life' part of the sky will induce the Tree to grow again.

... If, in the silence of the night, you should hear noises as of falling leaves and flowers, and afterward as of heavy fruit dropping to the ground, you will know that my prayer has been granted: the life of our little boy will be saved.' And having said that, Ulu fell on his face and died ...