Tribble

They were conceived by screenwriter David Gerrold and first appeared in 1967, in the fifteenth episode of the second season of Star Trek: The Original Series, titled "The Trouble with Tribbles".

The Klingons, in whose presence tribbles produce a convulsive, shrieking reaction, consider them "mortal enemies", as stated in the Star Trek: Deep Space Nine episode "Trials and Tribble-ations" (1996).

A Starfleet scientist, Edward Larkin, genetically engineered them into their current form, in an attempt to solve a planetary food shortage.

The experiment went disastrously wrong, resulting in Larkin's death, the destruction of his ship (overrun by tribbles), and the subsequent evacuation of the planet they were trying to save.

Shortly before the episode was produced Kellam de Forest Research pointed out the similarities between Gerrold's creatures and the Martian flat cats from Robert A. Heinlein's novel The Rolling Stones (1952),[5](p 271) and recommended purchasing the rights to the novel.

[5](p 274) However, Gerrold's account does not agree entirely with Heinlein's own recollection of the matter as related in private correspondence cited in his authorized autobiography.

A fan-made tribble