Kroot - Kroot Shaping: Perhaps the Kroot's most defining trait as a species is that they can alter their own biological evolution by genetically absorbing the traits and characteristics of other species, a process accomplished by eating their flesh. Due to this ability, the many Kroot warbands scattered across the galaxy often look radically different from one another, and can possess different abilities.Kroot leaders are known as Shapers; they are generally the Kroot with the instinctive ability to recognise desirable or detrimental biological traits in defeated foes and instruct their kindred in what to eat to suit them so that they might evolve themselves to better deal with the environment they currently find themselves in.For example, a Shaper who wants their Kroot to gain muscle mass will seek out conflicts with Orks to acquire Ork genetic material geared towards physical size, while extensive feeding on flying predators will allow the Shaper's Kroot to grow wings.This eating of their foes ties in with the religious beliefs of the Kroot: they believe that when a warrior of any species dies, his warrior spirit should be kept, and the only way to do this is by eating his flesh. The Kroot practice this in their funereal customs, in which the body of the deceased is consumed by the kindred.Kroot, who prey extensively on a particular species, will begin to take on the characteristics of that creature. In sentient species such as Orks and Humans, they may take on cultural aspects of that people as well.The Kroot digestive system is extremely efficient, capable of breaking down almost any organic material into an energy form that can be stored in specialised organs scattered throughout their bodies, called nymnes. Should anything inorganic and indigestible be consumed, the Kroot must regurgitate it with considerable discomfort.However, the strangest quirk of Kroot digestion is their ability to extract potentially useful strands of their food's DNA. Adeptus Mechanicus Genetors have long been aware that much of the double helix structure of DNA is used to structurally separate those regions of the genome that do contain usable genetic information. The Kroot have somehow inherited the ability to incorporate useful DNA sequences from other species into their own genetic makeup.The process is not an exact science, and there are many examples where it has gone awry, leaving some trapped in evolutionary cul-de-sacs, the existence of the Krootox and Kroot Hounds being the most visible evidence of this problem. At some point in their evolutionary history, both of these sub‑species of Kroot fed upon creatures that were possessed of traits they wished to take on but, in doing so, atrophied their intelligence.The Krootox are now much larger and stronger but became lumbering creatures, more akin to forest-dwelling herbivores than their smaller, more intelligent kin. The Kroot Hounds became faster and leaner, but, like the Krootox, their intelligence was reduced, becoming little more than vicious predators. The genetic baseline Kroot use these variants of themselves as labourers, pack animals, mounts, and even as weapons, especially the gargantuan Great Knarloc.There are other Kroot subspecies, such as the smaller, flying Kroothawk and the serpentine Krootworm, as well as other, more terrifying, creatures.Deep within the forests of Pech, there exist beasts that were once Kroot but have since descended hideous evolutionary paths to become monsters that feed on their own kind. Such places are considered cursed in Kroot culture, and only the bravest or most foolhardy Kroot ever venture within their haunted depths.Kroot are able to "taste" the taint in the meat of dead Genestealer hybrids, even if the hybrid's Tyranid features are not visible.Kroot are unable to effectively shape the necrodermis living metal of the Necrons, and doing so produces hideous effects as was demonstrated on the Kroot world of Caroch in 976.M41 when a Nanoscarab plague swept through the Kroot ranks, bursting from the bodies of those who had ingested the Necron bodies.There are at least three species that the Kroot have been forbidden to eat by their Shapers. These include:Tyranids - The Shapers have declared all Tyranid bioforms to be inedible (being declared inedible is as much a moral designation as a gastronomic one in Kroot culture), and because the Shapers are inherently repulsed by the Tyranid's particular way of changing their genetic makeup.Humans who worship Chaos.The T'au. The Kroot respect the T'au due to their role in saving the Kroot's homeworld of Pech from the Orks. As a result, consuming T'au flesh has been made a crime in Kroot society that brings swift and deadly retribution from the Shapers to any who violate the proscription.