Twice a week, I wear a pair of my retired running shoes to the gym. After work the other day, I was examining the treads of my shoes when I noticed an odd round piece of metal embedded almost exactly over the rear button of one of the shoes. I was almost floored after it was pried out; a rusty thing (about the size of a penny) with three large spikes. I must have stepped on it when walking either to or from the nearby parking garage. Ah, the great Pennsylvania outdoors!