Ambull

Ambulls are massively built, roughly humanoid creatures with an insect–like armoured casing and hugely oversized arms tipped with iron–hard claws. Their pronounced hunched simian stance lowers their true height greatly, but when fully upright with claws stretched overhead they can easily reach 4 metres. Ambulls are extremely hardy and long lived social creatures, usually forming close–knit family units with several adults tending to broods of 4–7 offspring. They are also natural tunnellers, with eyes sensitive to the faintest light and infrared spectrums and claws that can excavate through soft rock and earth at alarming speeds. Their communal tunnels and caverns can stretch for many kilometres underground, forming a vast network of what can appear to the unwary as safe havens from threats above the ground.

History
Most Imperial xenologists believe the species evolved in the deserts of the distant Death World Luther McIntyre IX in the Segmentum Solar. There, Ambulls primarily live underground during the harsh days, emerging at night (sometimes in packs) to scavenge and hunt, but also stalking any underground prey through their networks of tunnels. They can burst on their victims through the ground and smash with their huge arms, devouring flesh with their huge razor edged mandibles. Often they will drag the insensate body back to their burrow–nodes for the group to feed upon, especially immature Ambulls still learning how to hunt on their own. Ambulls favour live prey but are capable of eating almost anything they encounter.

Despite Delta-level bans on their transport, many ill–informed but ambitious groups (ranging from wealthy nobles to forbidden cults) have endeavoured to import and domesticate them as attack creatures or compound guards. Even when working with immature specimens, these attempts have always proved disastrous (often spectacularly so), usually resulting in groups of Ambulls escaping captivity to breed on their new planetary home. As almost any environment is less hostile than their native one and their new local prey both more plentiful and easier to hunt, they are known to breed at alarming rates and quickly become dangerous threats. One thing that Imperial xenologists have noted is that no matter where they are found, Ambulls show no sign of genetic drift or other morphologic changes. Even in the harshest, most radiological or polluted environments, these creatures remain unchanged, other than expected variations in colouring. Their extreme stability against the effects of mutation has been the subject of several intensive studies but with inconclusive results so far. The more radical elements of the Xeno Biologis even propose that the Ambull may represent an engineered breed designed to withstand Chaos. Wiser Adepts believe they are simply the result of the intense struggle for survival on their native hellish planet.

Source

 * Dark Heresy: Creatures Anathema (RPG), pg. 51