I stepped onto the deck of Sajik swimming pool and felt a sharp pain in my foot. It faded quickly and walked, limping a little, to the pool and swam. I limped back to the changeroom and had a look at my foot but couldn’t see anything. Later, at work but before classes started and students arrived, I had another look. I pulled out this little piece of broken glass – the lines on the paper are the standard distance apart for a notebook (click to bigify).