What does Zhouyi's fortune-telling earthworm mean?

Earthworms are mainly used in geomantic omen, because we see that geomantic omen uses a compass to determine the direction of mountains, that is, the direction. Geomantic omen turns the direction into 24 directions, that is, 24 mountains. There are yin and yang in all 24 directions. In order to distinguish them, the twenty-four mountains are divided into dragons, dragons and dragons. Lumbricus refers to A, C, G, benevolence as Yang, and Chen, Wei, Xu and Ugliness as Yin.