You are probably slightly aware of something moving around inside your violin, but here’s how it starts, as a mess in some deep corner.
Then next some of it gets loose, and starts moving around, and the rolling motion forms that shapeless bunch of stuff into balls. Sometimes they are just dust, or some hair, or maybe case lining (the green one up in the corner, in the photo below). As they roll around, they not only get larger, they get tighter and tighter–little felt balls sweeping the inside of your violin, keeping it relatively clean. Eventually, these end up in a drawer in some violin shop
The folk folks have a different problem than dust, and that’s bad vibes. However, rattlesnake rattles can chase those away. Really.