"“Underwalker” is the Makeb nickname for a species of subterranean insectoid carnivores. The shell of an underwalker is astonishingly resilient and shares the properties of some of Makeb’s ores. Biologists believe that the underwalkers may have mutated over millennia of drinking water contaminated by mineral deposits. Whatever they once were, underwalkers are a constant menace to Makeb’s mining engineers because underwalker territory is often around the richest seams of mineral wealth. More than one underwalker has been sighted with tools lodged in its carapace: the sign of tragic events occurring around a newly bored drill shaft."