Picture the scene. You're in the middle of a pop quiz in elementary school . You've accidentally written that 2+2=5 and you need to correct it, stat. What kind of eraser are you reaching for? Is it gnarly, gray and riddled with holes you poked in it? A fruity smelling one that coordinates with the rest of your stationery? Or maybe one of those weird putty ones that you stole off the kid next to you? There's no denying that this humble cornerstone of the average pencil case got us through some o…