Tnuctipun were small, mammalian, arboreal pack predators, averaging about 3–4 feet long. Their heads were long and lean, and their eyes opened laterally. They were highly intelligent (average IQ estimated around 130–140) and social. As befits their carnivorous nature, they were also ruthless, aggressive, and cunning. Their word for alien most closely translates to "food that talks".
The Tnuctipun invented most of the technologies from that era, including Stage Trees (trees containing solid rocket fuel in their trunks, originally used as cheap rocket boosters, now evolved to seed themselves across star systems), Slaver Sunflowers (flowers with integral parabolic mirrors that can focus sunlight to deadly effect), Food Yeast and stasis fields (a time dilation device). They were also known to have Total Energy Conversion (direct conversion of mass to energy) and a telepathy shield but these two technologies are legendary as no evidence has been found.
The Thrint came to be dependent on Tnuctipun technology. In order to for the Tnuctipun to think creatively, the Thrintun allowed them some freedom. The Tnuctipun used that freedom to stage a rebellion against their masters, the culmination of a carefully thought out, centuries-long plan, engineering species that were useful to the Thrintun at first, but eventually turned against them.
The true nature of some of their inventions became clear: Bandersnatch, thought to be non-sentient livestock, were in fact intelligent, created as spies immune to telepathy. Sunflowers turned against their masters and burned Thrint homes to the ground. Other Tnuctip inventions were designed to shape Thrint society to weaken it. Sunflowers encouraged a trend for the slavers to live in isolated manors, surrounded by slaves. Mutated racing Viprin (fast-running creatures raced for entertainment and gambling) ruined the existing viprin herding business, which along with other similar inventions led to an economic depression prior to the Tnuctip revolt.
The war escalated until the Thrintun, rather than accept defeat, employed a device that amplified the sphere of influence of a Thrint's mind control to encompass the entire galaxy. And they gave a simple command: Die. Everything in the galaxy that had evolved a backbone perished, including any Thrintun not protected by a stasis field. A still functioning suicide amplifier itself is discovered in the short story "Peter Robinson" by Hal Colebach, but it is destroyed.
Several other Tnuctip inventions are inadvertently discovered, including a prototype hyperspace shunt, discovered during the First Man-Kzin War. The Kzin lose the war before they can bring news of it home, and the device itself is lost.
The soft weapon was also of Tnuctip manufacture. It operated in a variety of modes and shapes. Various modes include a rocket stool, handgun, stunner, variable sword, high powered computer, an energy absorption field, a matter to energy conversion beam, and a matter to energy fueled self destruct mechanism.
It is theorized that the Tnuctipun were responsible for creating the Pak Protectors.