I love stuff like this. Consider that people had to have already invented knots, fine string (sinew, leather, or fibre), and figured out how to make small holes in easily shattered materials (even very hard shells are prone to chipping).

John in Kansas, the worm-holed shells may have been the first shells used as beads - kids today will string a found shell and wear it. But it's fairly easy to recognise the differences between holes made by worm and holes made by people, the placement is different because the worm is going for food and the people for display and balance, the tool marks are different, and when found in groups, as beads often are, they will be matched for size.