For those people like me thinking “WTF is a worry stone?”:

https://en.wikipedia.org/wiki/Worry_stone

Worry stones are smooth, polished gemstones, usually in the shape of an oval with a thumb-sized indentation, used for relaxation or anxiety relief.

Something one would fidget with when worried, I suppose.

In the same category, Greek beads on a string (not that, you pervs) and rosaries.