I believe when David encountered Goliath, he used a sling to kill Goliath. It is patch held on either side with a strand of leather. David swung it over his head in a circular manner and then released one of the cords (This detail is actually not in the Bible, but it helps you to understand. You can read the account for yourself in 1 Samuel Chapter 17. Make sure you are reading something that is clear). The flat rock embedded itself between Goliath's eyes -- or so the story goes.