common black millipede (Tachypodoiulus niger) 
Also known as the white legged snake millipede is a native and widespread species  found throughout the UK. It is a long, cylindrical millipede, typically 2–4 cm in length, with a smooth, shiny black or dark brown exoskeleton. Each body segment bears two pairs of legs, giving it a distinctive, many-legged appearance.
Tachypodoiulus niger is usually found in damp, shaded habitats such as woodland floors, gardens, and under logs or stones. It feeds mainly on decaying plant material, playing an important role in decomposition and soil nutrient recycling. When disturbed, it may curl into a tight spiral or release a mild defensive secretion. Active mostly at night or in wet weather, this species is an important decomposer in the UK’s ecosystems.