The metal heat spreader and small PCB make up the external features of an Intel CPU. You'll see they are terraced slightly to create two distinct resting areas on the CPU. The load plate, which holds the CPU in the socket, sits on the middle tier. The heatsink sits on the top tier, the CPU's heat spreader. That way, the two don’t touch.
A small notch here, as well as a symmetrical notch on the other side, and the aforementioned triangle, all help you place the CPU in its socket.