Narrative often draws inspiration from nature, most frequently in the form of Animal Motifs and Elemental Powers. There even are recurring animal-element pairings in fiction: for example, we have the Fiery Salamander or the Thunder Beetle. This trope is about one of such pairings, it's the link between tortoises and the ground.

This trope might exist as both the earth and tortoises are slow but extremely durable