Ah, Tribbles, those cute and cooing little furballs from the Star Trek universe that make pet lovers wish they could adopt them in real life.
Soft and gentle enough to make even Spock fall for their charm, they seem harmless enough, at least until they get a good meal and start copy/pasting themselves all over the place. They truly are fuzzy agents of chaos, so let's look back on a few times they seemed poised to take over the universe!
What is a Tribble?
Tribbles are furry, rodent-like animals that resemble balls of fluff, like long-haired guinea pigs, making it difficult to tell one end from the other. They originate from Iota Geminorum IV and their cooing has a calming effect on humans, much like a cat's purr.
Tribbles have no teeth but eat a great deal, and when they consume enough at one sitting, they will start to reproduce faster than a rabbit on a hot date. People are drawn to them because, as Dr. McCoy said, "It is a human trait to love little animals!" However, that "aww," moment is what gets most would-be tribble owners in trouble, no matter their intentions.
They nearly took over the Enterprise in 2268
Although tribbles weren't entirely unknown to Starfleet, as they'd been reported on ships as early as 2150. Cyrano Jones, a certified asteroid prospector and traveling salesman of sorts, was the man who brought them to Space Station K7 and the Enterprise itself. Once Jones reveals one in front of Uhura and Chekov, who are on shore leave to shop, Uhura cannot resist the tribble's cooing and takes it aboard the ship, thinking she's found a trendy new pet ("The Trouble with Tribbles" S2E13).
Soon after, Uhura discovers her tribble reproduced and gives away the offspring to other crew members on the ship. From there, they infiltrate Enterprise completely, as Scotty notes that they made their way into all the ship's systems, including the food processors. McCoy, who's been studying them, finally figures out that tribbles are born pregnant and will reproduce as soon as their bellies are full.
This leads to the discovery of a load of poisoned grain at the space station, as the tribbles who consumed it die shortly after. While Jones points out that the tribbles saved a lot of lives because he brought them onto the space station, he's left with the job of cleaning up the remaining tribbles, and Scotty beams the surviving tribbles into the engine room of a Klingon ship just to irritate the captain and his crew, with whom Scotty, Chekov, and a few other Enterprise crew members had fisticuffs with at the space station earlier.
Jones made the animals in "super tribbles" in 2269
In "More Tribbles, More Troubles" (TAS: S1E05), Cyrano Jones tries to reestablish his reputation as a tribble handler by altering their DNA so they wouldn't reproduce. He believes this will make them massively popular as pets, but the cheap methods he uses only make the animals grow to seemingly massive proportions. These new larger tribbles are part of one colony, and they manage to find their way onto Enterprise once again.
Once McCoy discovers the poor genetics involved, he injects the super tribbles with a vaccine that breaks them down into individual animals. This also controls how fast they breed, making them easier to handle.
Klingons destroyed the tribble home world in the 23rd century, as they hated these cooing creatures so much that they wanted to destroy the species completely. However, some did survive the culling, so maybe we'll see some more tribble-ations in future Star Trek series!