The pyramid is not shaped like a typical pyramid, because the bottom should be bigger and getting smaller on top.
The portion of a muzzle-loader rifle that fits against your shoulder is the - BUTT.
A muzzle-loader is a firearm in which the projectile and usually the propellant charge is loaded from the muzzle of the gun. This is distinct from the more popular modern designs of breech-loading firearms. That portion of a muzzle-loader rifle that fits against ones shoulder is called the butt.
The branching point on a cladogram represents a common ancestor. A cladogram is a diagram used in cladistics to show relations among organisms. However it is not an evolutionary tree since it does not show how ancestors are related to descendants, nor does it show how much they have changed.