The Class Diplopoda comprises millipedes, terrestrial arthropods characterized by elongated, segmented bodies with two pairs of legs per segment. They are mostly slow-moving detritivores, feeding on decaying plant material, and play an important role in nutrient recycling in soil ecosystems. Millipedes have a hard exoskeleton, simple eyes, and can secrete chemicals for defense. They are generally harmless to humans and are found in moist habitats worldwide.