Tribble

Tribbles are fictional alien species in the Star Trek universe who first appeared in the episode titled "The Trouble with Tribbles". They are depicted as small, furry, soft, gentle, attractive, and slow-moving, and they usually produce a soothing purring or cooing sound when stroked, all of which are endearing traits to humans, Vulcans, and their hybrids. However, because tribbles reproduce incredibly fast, and consume exponentially larger and larger amounts of food as they multiply and crawl stealthily from one place to another, Starfleet considers them dangerous organisms and forbids their transportation. The Klingons, in whose presence tribbles produce a convulsive, shrieking reaction, go as far as to consider them "mortal enemies", as stated in the Star Trek: Deep Space Nine episode "Trials and Tribble-ations".