Hexagon

Origins
In scene 280, the three fronds are connected together: The Third Frond is slid into place with the other two Fronds, filling in the 1/3 vacancy. In scene 283, it's observed that once the three fronds are interconnected, a Hexagon is seen to grow between them: The SET OF 3 FRONDS quietly churns in the cave. A 6 INCH HEXAGON is growing from its center where the Leaves of each Frond meet. Shortly, in scene 284, the Hexagon is seen to grow of it's own accord: The Set of 3 Fronds sits alone. The Hexagon has grown twice as wide and to a height of 10 inches.

Purpose
By scene 300, we learn that the Hexagon has grown into another Circle Frond, like that found inside the maker.