Hi Michael, I am no expert or scientist, but I think the pyramid is
mainly  a result of how the bottom of the cell meets with the bottoms of the
cells on the other side of the comb.
    If you look at a natural comb in the light you'll see that the three
sides of the hexagon meet right in the middle of the cell on the opposite
side witch create the pyramid but as you look toward the sides of the comb,
you'll see different shapes probably not as structurally (that's a tough one
to say ) strong.
    Hope this helps.
                            Normand