Ideas:

These two figures, probably sharks (mango), are obviously counterparts to

and in both texts the creature to the right is fatter than the one to the left. Is there a difference in meaning between these pairs of 'half-moon twins'? I think so. Different appearances probably represent different meanings. Perhaps a 'shark' is the dark part of the Moon and the other creature the light part.

"Fetu-tea [Pale Star = Saturn] was the king. He took to wife the dome of the sky, Te-Tapoi-o-te-ra'i, and begat stars that shine (hitihiti) and obscure, the host of twinkling stars, fetu-amoamo, and the phosphorescent stars, te fetu-pura-noa. There followed the star-fishes, Maa-atai, and two trigger-fishes that eat mist and dwell in vacant spots in the Milky Way, the Vai-ora or Living-water of Tane.

The handsome shark Fa'a-rava-i-te-ra'i, Sky-shade, is there in his pool and close by is Pirae-tea, White Sea-swallow (Deneb in Cygnus) in the Living-waters of Tane." (Makemson)