Tribble

Tribbles are fictional asexual animals in the Star Trek universe who first appeared in the episode titled "The Trouble With Tribbles". They are depicted as small, soft, and gentle, and produce a soothing purring sound. These traits are said to endear them to most sentient races which encounter them, with the notable exception of Klingons, who consider tribbles to be "mortal enemies" of the Klingon Empire, as stated in the Star Trek: Deep Space Nine episode "Trials and Tribble-ations".