"GIVE THE SQUIDDIES NO QUARTER."
- – General Kojhmar on the war against the Thyrrus, propaganda poster
"What the fuck is that thing doing?"
- – Anonymous guardsman, after watching a Thyrrus warrior dance around a fire while making mating noises
The Thyrrus (or Histrio Tragoedus, according to Magos Biologis Darvus) are a xenos species of cephalophod-like beings, first located on the Segmentum Pacificus around 784.M41, where they fought the Imperial Guard. This species is remarkable due to being one of the weirdest aliens Mankind has ever made contact with, and considering the amount of weirdoes that populate the galaxy, that says something.
A Thyrrus specimen is heavily described in Xenology by Magos Biologis Sharle Darvus. According to the researcher, Thyrrus have a cartilagenous body, with a lot of tentacles both on the upper and lower parts, probably used as means of locomotion. They have two pairs of proper arms, each one having multiple joints, ending up on three/four-fingered hands. They have four eyes, suggesting 230º peripheral vision. They don't have any form of endoskeleton or exoskeleton, the weight of their bodies supported by a cartilagenous spine. This means Thyrrus are quite squishy, although this doesn't mean they're fragile creatures. They eat through a process of osmosis done by a series of organs located on their... mouths?... They also breath by the same means, looking like a system close to the ones used by jellyfish, although much more complex.
They seem to be adapted to live in extreme locations and climates, adapting quite easily to extreme conditions. They are able to adapt their bodies according to atmospheric, gravitational, and geographical conditions on the planet they're in. They also can change the colours of their body at will, probably with a social purpose rather than camouflage. They are basically the result of a squid and a jellyfish mixed together and then put on the microwave to melt.
Society and Behaviour
The Thyrrus' way of life centers around show and spectacle. They seem to think that life is just a big performance, either as a big elaborate play or some game being played by neckbeards on their spare time, so they've just decided to have fun while they're at it. They have no concept of victory or defeat, and every single aspect of their lives, from the battlefield to cooking is interpreted as a show. Thus, it is pretty common for the Thyrrus to just try to make as many lights and noises at every opportunity, regardless of the sense that makes. They can blow up a building trying to cook dinner, but the place looked so pretty while burning...
In warfare it seems they don't care who actually wins so long as the battle is really freakin' cool. During the fights against the Imperial Guard on Segmentum Pacificus, the Thyrrus were a quite imposing opponent, with their threatening looks and their plasma weaponry... only for them to start doing weird shit that worked to their detriment (probably their equivalent of drinking and dancing during battle), which left the guardsmen wondering what the hell was going on. Due to this, and because of their weird shape, they gave the Thyrrus the nickname of "Squiddies". Which is adorable.