The cylindrical body of this millipede measures up to 47 millimetres long and up to 5 millimetres wide, and is divided into a head and a trunk. The latter consists of between 44 and 54 segments. Each segment has two pairs of legs, from which this group of arthropods gets its name: diplopoda. The Rossiulus kessleri varies in colour from dark grey (almost black) to bright grey (usually young millipedes). When threatened, it coils itself into a spiral disc with its head to the inside. To protect itself from predators it has defensive glands on the sides of each segment, which secrete hydrocyanic acid with admixtures of other toxins, which cause severe irritation to the eyes and leave yellow or purple stains on the hands, with a strong almond smell. The body of the Rossiulus kessleri has a strong calcinated armour.
This environmentally flexible species spreads from the Kola Peninsula to the Caucasus, and from Central Ukraine to the Urals.
Rossiulus kessleri lives in the steppes, in the upper layer of the soil and in leaf mould, with as many as 200 to 300 per square metre. It is a typical saprophage, feeding on fallen leaves, decaying leaf parts and grass debris. Along with the earthworm, it plays an important role in the humification of the forest floor and in improving soil fertility. After mating in June, females lay eggs in specially built chambers in the soil, from where the young hatch in a few weeks with several segments and a soft body. As they grow, the young regularly shed their skin (ecdysis), and the number of segments grows. Diplopoda are the only invertebrates in the world characterised by periodomorphosis: in unfavourable conditions the male kessleri moults and reverts to a sexually immature stage. When favourable conditions return, it once again moults and returns to the adult state. This lengthens its overall lifespan by one and a half to two times.