I was digging through the old parts that I have sitting around and I stumbled across my old rotors and pads. Since I was buying new rotors and pads I let the previous set wear very low.
This is one of the front pads. The wear indicator studs are clearly visible and it looks like part of one of the indicators has managed to rip the pad through the centre.
This is reflected pretty badly on the rotor as well.
It appears the studs are a lot harder than the rotors. A good reminder to replace the pads before they wear too much as it will be cheaper to replace them rather than a whole rotor.