yes, they do almost form a perfect square.
they are removed with a special instrument - it's hard to explain in words, so take a look at the link.
there are two jaws. an upper and a lower.
the lower jaw is a single 'blade' and upper jaw has two 'blades'
so imagine a pair of pliers - when you squeeze them together the lower blade fits between the upper two blades.
the lower blade is then placed under the staple, which stabilizes the middle of the staple. The top two blades come down as you squeeze the handle, which then bends the staple uppward and outward - effectively reversing the force and direction of how is was applied.