Ermine
An ermine was a species of weasel native to the northern hemisphere of Earth. They were characterized by having brown fur that turned white in the winter. This creature, much like a tribble, was described as being "nice, soft, and furry."
After Leonard McCoy made such an assessment with regards to the "practical use" of tribbles in 2268, including the fact that they "make a pleasant sound," Spock retorted that "so would an ermine violin, but I see no advantage in having one." (TOS: "The Trouble with Tribbles")
The painting by Leonardo da Vinci, "Lady with an Ermine", featured a woman holding this creature. (VOY: "Scorpion", "Concerning Flight")