Tholian Assembly
The Tholian Assembly is the xenophobic interstellar government of the Tholians, a crystalline-based non-humanoid species. The territory of the Assembly includes the region of space known as the Tholian sector. The xenophobic Tholians are a belligerent power that’s known for aggressive expansion and for intractable defense of their declared territories. The Tholians do not maintain friendly relations with any other known species.
Government
The Tholians refer to their territory in space as "The Territorial Annex of the Tholian Assembly," suggesting that their expansion is one of conquest rather than mutual interplanetary agreement. Areas of deep space are repeatedly claimed by the Tholians as their own. Little is known about Tholian culture; it seems to be based on land ownership and some sort of governing aristocracy - but some traffic indicates that every Tholian is a member of one or more "subassemblies" within the Tholian Assembly with crucial responsibility in its own area.
During several confrontations between the Tholian Assembly and the United Federation of Planets, Starfleet officers have perceived the behavior of their Tholian counterparts as aggressive and territorial. The Tholian government is known to kill outsiders caught entering Tholian space without their consent. The Assembly is also known to annex systems outside Tholian space, to further isolate their territory. The Tholian Assembly remained neutral for the duration of the Dominion War, though before, during, and after they maintained a diplomatic presence amongst the Alpha Quadrant powers, sending envoys and maintaining an embassy on Deep Space 9.
The Tholian "web," an intricate netlike force field, is the primary weapon of the Tholian space fleet. Through a process unknown to Federation science, two or more vessels can weave a tractor web around a vessel and tow it back to port. Once completed, the web cannot be broken by conventional weaponry.
Physiology
Tholians are a crystalline species, with a hard carapace that was chiefly mineral. There are six thin legs that make it possible for the being to move in any direction quickly; the legs are articulated with joints roughly corresponding to the knee and ankle of humanoid species. Each leg ends in a multi-toed foot. The legs are attached at the base of the torso and are radially symmetric. There are two arms; each has joints analogous to the humanoid elbow and wrist, and each arm ended in a multi-fingered hand. There is a slightly visible neck that is covered by a semi-transparent dome membrane that shields the head. Tholians have two glowing spots near the top of their torso, which they turn to face individuals with whom they interacted, suggesting they were some sort of information-gathering organ(s) or receptacles.
Tholian biology requires high temperatures around 480 Kelvin (207°C). They can tolerate lower temperatures for a brief period of time; if they are exposed to temperatures around 380 Kelvin or less, their carapace would fracture. In temperatures even lower, a Tholian will freeze solid and shatter. Tholians communicate primarily through a series of clicks and chirps. They are also naturally able to emit various forms of radiation, which they can modulate. Tholians can communicate over short distances in this fashion.
