A geosonic was a device created by Humans on Earth.

They were handheld portable devices designed to aid individuals in excavations. Created with the intention of removing rocky obstacles, the geosonic was typically placed on a rocky obstruction where the central cylinder drilled into the surface after which it attempted to find the correct sympathetic harmonc signal. Once achieved, the device created sonic waves that destroyed the rocks in its path. However, some locations were too unstable for the geosonic to work. (Episode: The Secret of Strand Hill)