Strange button on wire
 

Hello all.
I was removing the floor carpet on the driver's side and to do this easier I had to remove the plastic panel above (where the hood release handle and ODB port located).
When I removed this panel, an strange wire with some kind of button(?) fell out. Does anyone know what this could be?

https://cimg5.ibsrv.net/gimg/www.mbw...5a5923e2b5.jpg