From The Crop Circle Ship Wiki
23rd of April at Hampshire, 1999.
This formation is the clearest technical example we have showing such high detail of an arm from the Large Tetrahedron Structure.
Below, the object highlighted in the yellow square is the Watersphere. This object exists at the very center of the Large Tetrahedron Structure. If you look closely, you will notice half of a circle (in the white square below). The other half of this circle appears to be hidden behind the 'pipe'. This tells us that the object (the Watersphere) is 'behind', or not in the same sequence as the other objects (not in line with S1, S2, S3, etc).
The next image compares the formation directly to the Large Tetrahedron Structure.
 See also