This type of glyph is found in four examples in Keiti:

Eb1-40 Eb3-34 Eb3-37 Eb8-20
 
If I had to guess what is shown, I would say that we see a shape representing the beginning: At the bottom of the orbit (not shown in toto) there is a nut, and that nut is below the surface of the earth (wedge-shape above the nut), with a little sprout in the middle striving up towards the light. But that is pure guesswork, or?
 
Behind this guess of mine there are lots of threads. First of all I would like to refer to a picture I have seen reproduced in more than one book, showing a place for sacrifices, where in the background there is a field studded with objects resembling this glyph. The picture is from Cook's first voyage.
 
In Van Tilburg's book I found a picture of a human skull on top of which a sign similar to this glyph is incised. Cranium = nut in Polynesian thought, which I have told already at the start of this voyage. Life needs death.
 
I think that the general structure of this type of glyph closely resembles the full-moon-glyph in Mamari:

The principal god of Easter Island, Makemake, also seems to be involved.