Upon a suggestion by Donald, Scrooge has a shaft dug beneath his money bin to search for faults which might get cracked open by a tremor, but the miners are suddenly frightened away by voices coming from a gigantic cave.

In the caverns below Duckburg, Scrooge and his nephews soon discover that the smooth "rocks" are really subterranean beings calling themselves Terries and Fermies who look like bowling balls with arms and a head, but no legs, and move around by rolling on the ground.

In an attempt to stop the earthquakes, Scrooge steals the trophy, but is forced to discard his top hat during the subsequent escape.

"However," Andrae writes, "the story differs from its predecessors in situating its fairy world in a realm that is tied to and affects the everyday one.

The geologic realm in literature has come to represent the psychologic, and this story deals with the repressed longings that underlie the civilized psyche."

He goes on to say that "the Terries and Fermies represent the repressed desires that undergird the Protestant ethic, fusing work and play and functioning as emblems of unalienated labor.