(tih-YES-in) Sapient, spacefaring race. Their home-world is located approximately 3,500 light-years from Sol, though their political volume of influence borders considerably closer, slightly more than 1,000 light years distant.

TiYessin are facultative bipeds as opposed to obligate. That is, they normally walk upon their hind limbs, but are equally facile upon all four, if not faster. They are exoskeletal and endothermic. Their skin is a pale bone-white, with yellow tints on hands, pads and other flexible external areas. They have segmented bodies, with some sections specialized to different purposes. They rely primarily upon sight, and their sense of hearing is roughly equivalent to that of humans.

Adults stand between about meters in height, with an overall length approaching 3 meters. They are very flexible, despite their exoskeletal nature, and can compact themselves comfortably into surprisingly small areas.

TiYessin possess four limbs in total. All four can be used in locomotion. When walking, or holding objects, TiYessin prefer to walk upon their hind limbs, using their tail for balance and occasional support, similar in motion to a kangaroo. When speed is required, or the circumstance calls for it, TiYessin adopt a four legged gait that is quite rapid. Their legs (and arms) each possess an extra joint compared to humans, and they can store quite a bit of spring energy. TiYessin are excellent leapers.

Only the forelimbs are prehensile. The feet are more claw-like. There are a number of hook-like protrusions along each limb. The ones at the joints are often used to help hold objects, though they cannot manipulate anything with facility. The hands have two fingers and an opposable thumb. The material of the hands is similar in composition to the skeleton, but softer and more flexible. Their grip is not particularly strong.

The Tiyessin head has a triple-jawed mouth, eyes with good binocular vision just below the lower jaw, and two anterior nostrils. They have no external ear structure.

The Tiyessin are primarily exoskeletal. The physical make-up of their skeleton has no precise earthly analogue. It is soft in infants, flexible in adolescents, and hardens into rigidity throughout adulthood. There are fifteen segments. Each segment has four plates, arranged to make a rough tube. The ventral and two lateral plates are fixed in size at the onset of adultood, and any subsequent growth is done by the dorsal plate. This dorsal plate is similar to a turtle's shell in design (though not composition). It is composed of smaller interlocking plates that grow by adding rings of material. Thus a very large or old TiYessin might possess quite elaborate or horn-like “back bumps”. This can be used to intimidate others, as it is viewed as a sign of physical prowess.

There are a number of specializations to each section.

1. Cranial - Contains brain, mouth and primary sense organs. The nostrils and mouth take air into a bladder that is used for vocalization, but is not critical for respiration.
2. Gastro-cervical (2) - The main organs of digestion are here. More below under “Diet”.
3. Shoulder - The forelimbs adjoin the body here, and most of this structure is given over to support and muscle anchoring.
4. Thoracic (5) - Most of the respiration and circulation of blood and nutrients is handled here. There are a number of supplemental digestive organs as well, though they do not handle bulk material, merely the nutrients extracted from the gastro-cervical segments. There are four nares for respiration in each segment, two to a side. TiYessin do not have lungs as we understand the term. A TiYessin can survive without using all of its breathing apertures, but is increasingly uncomfortable.
5. Hip - Similar in most respects to the shoulder, escept the legs attach here
6. Caudal (5) - The tail has five segments, the last being a thick, flat pad. The bottom of this pad is softer, similar to the hands and pads of the feet. It is likewise sensitive to vibration. A TiYessin who is intent on sensing vibration will stand very still with the tail pad firmly planted. The caudal segments tend to stiffen with advancing age, becoming nearly fused towards the end of the natural life span. Pad sensitivity is likewise lost. Modern medical techniques alleviate much of this.

TiYessins possess the same basic senses as humans, though their exoskeleton has very little sense of touch. However, sensitive nerves at the tips of their legs and upon their thick tail pad allow them to feel vibrations in the ground around them, giving them a complete sense of creatures moving nearby. This is a trait they share with the Mordeth. They have an acute sense of taste.

TiYessin do not seem terribly picky about the specific plants and animals they eat. Their complex digestive system allows them to consume almost any organic matter and easily passes anything they cannot process. They do not excrete waste as most races do. Instead, they vomit capsules of undigested matter several hours after eating. The TiYessin mouth can open very wide, since the two upper mandibles lift up and away from the fixed lower jaw. The tongue is likewise tripartite, and fairly strong and dextrous, possessing knobby tips almost like stubby fingers. Most of the primary digestive organs are located in the two sections segments the head and the shoulder segment. There are digestive support organs in other segments, but these would be more similar to the human liver, pancreas or spleen, while the two “neck” segments contain the analog to the human gastro-intestinal tract.

TiYessin do not have teeth, but the bony plates of their jaws can break up most food.

Like humans and most other races, TiYessin have both males and females. Mating is typically for life, though occasionally mates will depart from each other if situation necessitates.

Children are laid in clusters of small eggs, usually six at a time. They will hatch as tiny creatures, no more than a few centimeters long. They have tremendous appetites and will eat almost constantly for the first year of their life, rarely pausing even for sleep. This is necessary since they will grow at an incredible rate, being full-sized adults within just a few years.

Parents share the responsibility of rearing the young, protecting them and teaching them necessary skills. They share strong familial bonds, and separation is often emotionally difficult.

Despite their outlandish appearance, TiYessin are psychologically closer to humans than any other race in the galaxy. They are passionate, individualistic, and richly diverse. They share humanity's creativity, emotional energy, and unpredictability. They are ambitious, idealistic, and socially fractured.

They also have strong familial bonds. Mates feel deep love for each other and will only separate under the most severe circumstances. Children are loved dearly and grow close to their parents. Though they age quickly, it is just as hard for parents to let them venture into the world as it is for humans.

There are, however, two psychological features that distinguish the TiYessin from humans.

First, TiYessin are high-spirited and lively creatures. They sleep only a few hours a day and seem to have boundless energy the rest of the time. They play often and enjoy active sports such as climbing, running, and tussling. They are usually full of good humor and have a knack for seeing the brighter side of life.

Second, fear plays a very weak role in TiYessin psyche. Their social interactions are not complicated by anxieties of rejection, self-invented masks, or hidden emotions. They feel no apprehension about the future. They don't search hard for meaning in life, feeling it's so simple and obvious that it doesn't take much effort to find. They try to find the most uncomplicated road through every trouble in life and approach it with the bravest heart.

TiYessin art is as diverse as their race, ranging from the complex to the simple. It includes carvings, images, written word, and performances. It covers an amazing range of subjects from tragedy to comedic inspiration. All of it, however, seems to center around forever capturing fleeting emotions and memorable moments, enshrining them as a part of their culture.