This is a penny coin (1p) minted in 1973. It was examined in the electron microscope in August 1999 and shows the wear due to over 25 years of continuous use. The numbers have become blurred and the edges are losing their sharpness. As you zoom in you will see a deposit that has become trapped in the corners of the numbers. This is made up of skin cells of the thousands of people who have handled this coin over its lifetime!
Compare this coin with one minted in 1998.