If you go into some really old cemetaries and find some of the "slabs" with what look to be decorative holes in them about 3/8"-1/2" round that's the holes that the string went through. They're just about the size that you can stick your finger into but don't---sometimes some pretty nasty spiders make their homes in them. If you think it's a string hole you can use a small stick to see if it goes all the way through. There are some graves with these in an old cemetery that we went to last year in S. Carolina.