The first two pages in the hua poporo part of the glyph dictionary:

The two plants in focus are here introduced, poporo and kuru. From the top of the head of Ku a small green kuru shoot appeared. I remember that headhunters developed a disease named kuru.

"... Upon the death of an individual, the maternal kin were responsible for the dismemberment of the corpse. The women would remove the arms and feet, strip the limbs of muscle, remove the brain and cut open the chest in order to remove internal organs. Shirley Lindenbaum, one of the early kuru researchers, states that kuru victims were highly regarded as sources of food, because the layer of fat on victims who died quickly resembled pork. Women also were known to feed morsels - such as human brain and various parts of organs - to their children and the elderly (Lindenbaum, 1979).

It is currently believed that kuru was transmitted among the South Fore through participation in such cannibalism, although opportunistic infection through wounds when removing infectious tissue from the corpse can be assumed to be another cause, as not all cases can be explained by ingestion of infectious tissue. Though the Fore would not eat those who had apparently died of disease, and so did not so easily catch other diseases via cannibalism, they believed that kuru was a mental affliction caused by a curse rather than a physical disease.

The kuru epidemic reached its height in the 1960s. Between 1957 and 1968, over 1100 of the South Fore died from kuru. The vast majority of victims among the South Fore were women. In fact, eight times more women than men contracted the disease. It later affected small children and the elderly at a high rate as well ... The disease all but disappeared with the termination of cannibalism in New Guinea ..." (Wikipedia)

Sinking down, feet first, until only the 'inverted bowl' of the top of the head was left visible we recognize from Ogotemmêli:

'... But in the fullness of time an obscure instinct led the eldest of them towards the anthill which had been occupied by the Nummo. He wore on his head a head-dress and to protect him from the sun, the wooden bowl he used for his food. He put his two feet into the opening of the anthill, that is of the earth's womb, and sank in slowly as if for a parturition a tergo.

The whole of him thus entered into the earth, and his head itself disappeared. But he left on the ground, as evidence of his passage into that world, the bowl which had caught on the edges of the opening. All that remained on the anthill was the round wooden bowl, still bearing traces of the food and the finger-prints of its vanished owner, symbol of his body and of his human nature, as, in the animal world, is the skin which a reptile has shed.

Liberated from his earthly condition, the ancestor was taken in charge by the regenerating Pair. The male Nummo led him into the depths of the earth, where, in the waters of the womb of his partner he curled himself up like a foetus and shrank to germinal form, and acquired the quality of water, the seed of God and the essence of the two Spirits ...'

In the Tahitian language ulu means the skull and uru breadfruit:

We should remember Mokuola whose life was saved by the death of his father Ulu, the head of whom was buried close to a spring of running water:

"When the man, Ulu, returned to his wife from his visit to the temple at Puueo, he said, 'I have heard the voice of the noble Mo'o, and he has told me that tonight, as soon as darkness draws over the sea and the fires of the volcano goddess, Pele, light the clouds over the crater of Mount Kilauea, the black cloth will cover my head. And when the breath has gone from my body and my spirit has departed to the realms of the dead, you are to bury my head carefully near our spring of running water. Plant my heart and entrails near the door of the house. My feet, legs, and arms, hide in the same manner. Then lie down upon the couch where the two of us have reposed so often, listen carefully throughout the night, and do not go forth before the sun has reddened the morning sky. 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.

His wife sang a dirge of lament, but did precisely as she was told, and in the morning she found her house surrounded by a perfect thicket of vegetation. 'Before the door,' we are told in Thomas Thrum's rendition of the legend, 'on the very spot where she had buried her husband's heart, there grew a stately tree covered over with broad, green leaves dripping with dew and shining in the early sunlight, while on the grass lay the ripe, round fruit, where it had fallen from the branches above. And this tree she called Ulu (breadfruit) in honor of her husband. 

The little spring was concealed by a succulent growth of strange plants, bearing gigantic leaves and pendant clusters of long yellow fruit, which she named bananas. The intervening space was filled with a luxuriant growth of slender stems and twining vines, of which she called the former sugar-cane and the latter yams; while all around the house were growing little shrubs and esculent roots, to each one of which she gave an appropriate name. Then summoning her little boy, she bade him gather the breadfruit and bananas, and, reserving the largest and best for the gods, roasted the remainder in the hot coals, telling him that in the future this should be his food. With the first mouthful, health returned to the body of the child, and from that time he grew in strength and stature until he attained to the fulness of perfect manhood. He became a mighty warrior in those days, and was known throughout all the island, so that when he died, his name, Mokuola, was given to the islet in the bay of Hilo where his bones were buried; by which name it is called even to the present time." (Campbell)

Unqestionably there is a close link in thought between a breadfruit and the human head.

The breadfruit tree grew up before the door, not where the head of Ulu was buried. From the head - it seems - bananas grew. In between were sugar-cane and yams:

We note with satisfaction that Metoro's words uhi (tapa mea) and toa (tauuru) agree with yams and sugarcane - the limbs of Ulu, presumably, corresponding to the 'limbs' of the solar cycles. The head gives nourishment to the banana (probably moon), while heart and intestines nourish the breadfruit, which returns with 'heads' to complete the cycle.

Could, possibly, the top part of the head - still visible after the rest has disappeared under ground - be the 'banana' (sunlit part of the moon)?