Zoat

Zoats were a species that were enslaved by the dreaded Tyranid. They were centaur-like appearance, standing upon four legs and manipulating objects with two forelimbs that form their stocky arms. Because they are only slightly manipulated by their Tyranid enslavers, they do not possess the exoskeletons of their masters and instead have a thick scaly skin for their bodily protection. Overall they stand taller than a man and are extremely muscular, and are more than a match for most others in combat. They are also equipped to be proficient in ranged combat, having access to a number of weapons and the skills to be equally deadly with each. One weakness that they do suffer from is their inability to breathe all but a highly specific atmosphere, forcing them to wear respiratory masks in order to survive. They are extremely intelligent and have high-developed brains, allowing them to not require the control of the Hive Mind; as such they can travel ahead of the Hive Fleets as scouts and originally as diplomats. Even so as they are still Tyranids they have strong inherent psychic powers, chiefly telepathy. These powers differ from other Tyranids though as they are capable of communicating with members of most other races via their telepathy. They seem incapable of communicating verbally.

First Contact and Subsequent Extinction
During the 38th Millennium, the Imperium of Man first came into contact with the Zoat. During these days half of a Tyranid force would be made up by the Zoats. The Zoat were unlike most of the Tyranid's assimilated worker-creatures, having independent thinking, allowing them to by used by the Tyranids as a type of ambassador. Because of this the Zoat were the first members of the Tyranid race to make contact with the Imperium of Man. First contact was made with the Imperium as early as M38 in a fleet of semi-organic spacecraft attempting to enter Imperial Space, claiming to be escaping slavish oppression. It is clear that via their initial contact the Zoats did not declare their true intentions, nor the true intentions of their masters, although it foreshadowed their ultimate task.

It is possible that as the Hive Fleets evolved more, the Zoats became less and less of a useful tool, their free thoughts becoming an undesired quality. Many Zoats, sensing that they would soon reach the end of their usefulness to their brutal masters and that they would be fed back into the Tyranid bio-mass never to be recreated again, and therefore staged a rebellion. This rebellion was quickly crushed and the rebels were soon purged from the Hive Mind's forces. Those who survived this purging fled ahead of the main Hive Fleets and made up that first fleet, although they were soon trapped between their former masters and their new aggressors they met who stupidly saw them to be an invading force. Being warlike by nature, the Zoat reacted in kind and so ultimately allied themselves against the Imperium regardless.

As the Tyranids became a more common sight in the galaxy after the invasion of Hive Fleet Behemoth, the Zoats were no longer seen outside the ranks of the Tyranids, indicating that the rebels were wiped out. The sightings of even these Zoats became less and less frequent and they disappeared entirely from Hive Fleet Leviathan. If the only Zoats to have entered the Galaxy were those of the initial fleet, Hive Fleet Colossus, then their absence can be explained as the last known vessel of that fleet was destroyed above Zorastra in 226.M39 after the fleet provoked the Zorastra-Attila war.

Technology
Zoat technology appeared to be a very unusual cross between symbiotic, organic devices and entirely mechanical devices. They were capable of carrying living weapons such as Fleshborers and Boneswords as well as more standard mechanical weapons such as Flamers and Missile Launchers at the same time, indicating their strength. Their spacecraft also displayed this odd mixture, being only partially organic. These ships looked like a conch and were grown, but at the same time were inanimate in that they are formed from stone rather than the bone-like material Tyranid ships are generally made from. A potential reason for this is their independence from the Tyranid race as a whole and the need to interact with the rest of the universe around them without the influence of the Hive Mind, wherein the typical Tyranid ships are in fact Tyranid species and thereby require the Hive Mind to function. Either way, their dependence on inorganic technology is now complete, as all Zoats appear to have to wear respirator masks in nearly all atmospheres.