From The Crop Circle Ship Wiki
Note: The terms Octahedron and Pyramid may be used interchangeably throughout the crop circle ship material.
The shape is like two pyramids connected to each other at the base.
This is referred to as 'The Octahedron in the Watersphere', or sometimes, just 'The Octahedron'. It exists at the center of the Watersphere, and therefore at the center of the Crop Circle Ship itself.
 How to identify
Squares represent the Octahedron.
On a rare occasion, a direct octahedral design also provides an obvious hint.
 The octahedron in 2004 and 2005
In the 2005 formation below, there are 4 groups of lines (shown inside the light blue borders).
Each of these groups has a total of 13 lines, giving a grand total of 52 lines.
This number of 52 represents the slope angles of both parts of the Octahedron.
We can imagine cutting out the formation on the left, below, and constructing it upright as a pyramid over its base on the right. These formations were created only a few days apart from each other.
The following symbols also represent the pyramid.
 Magnetic differences
In Secrets to the Fields, Freddy Silva writes:
"In the year 2000, an octagonal formation at Silbury Hill had a sixty foot diameter central spiral overlaid with four smaller double spirals at various points, each effectively creating infinity symbols.
 See also