Poor Mark xD
I Had a Pawn Cube!
I'm pretty sure one of those happened in one of Fischer's games, but in the center (e4,d4,e5,d5).
Finally! A relevant post! Thank you @blueemu! XD

Since the purists and pedagogues object to the term "pawn cube", perhaps we should call it a pawnahedron.

If we assimilate each pawn to two points. One at the top one at the bottom representing the two separate centers of mass then it's a parallelepiped. Seen as pawns have an axis of rotation both centers of mass are lined up and with the pieces upright they form a cuboid. That's only with the very reasonable analogy of the pawn having two big areas of mass one at the top and one at the bottom.
If the pawn's heigh is equivalent to the distance in between two adjacent pawns (width of a pawn plus distance in between two pawns) then it can be assimilated to a cube.
So although it would be more accurate to say a pawn cuboid a pawn cube is a reasonable claim as long as you state initial parameters.
8 hemispheres 8 cylinders and 4 spheres when arranged equidistant to each other at 90° don't make a square much less a cube