Iota Geminorum IV (also known as Fafniri to the Klingons, and referred to as Tribble Prime on star charts) was a planet near the borders of the Klingon Empire, which was the home world of the tribbles.
In the Nero-created alternate reality, the Klingon Empire attempted to exterminate the tribble population of the world in 2259. The crew of the USS Enterprise visited the world, the first exploration of the world conducted by the Federation. (TOS comic: "The Truth About Tribbles, Part 1")
In the prime reality, between 2267 and 2285, the tribble population was replenished by animals transported off of Deep Space Station K-7. (TOS short story: "The Last Tribble"; TAS novelization: More Tribbles, More Troubles; ST reference: Star Charts)
- This planet name appeared on a background graphic in Keiko O'Brien's classroom on DS9, but was never spoken in dialogue until 2019. In the comic "The Truth About Tribbles, Part 1", the planet's name is spelled Iota Germinorum; It is unclear whether this is a mistake or the planet's name is different in the alternate reality.