You searched for: “geophone
geophone (s) (noun), geophones (pl)
1. A seismic device used to detect vibrations in the Earth: A geophone is an instrument used for detecting sound waves underground.

A geophone is a seismic transducer that responds to motions of ice, soil, or rock at locations on or below the surface of the ground.
2. In music, a drum that is filled with pellets: Jack swung the geophone around to make sounds like earth shifting from one place to another.