A mysterious ruby that is said to bring good fortune to its bearer. Takes the form of a small, furry creature that leads the summoner to the other avatars.
The ability to summon Carbuncle is one of the basic summoner abilities, and is available from level 1 as soon as the job is unlocked from the quest I Can Hear a Rainbow (which is centered around summoning Carbuncle from his ruby).
Many arguments over what type of animal Carbuncle is have led to a Japanese flying blue squirrel known as a Momonga.
Carbuncle, originally was spelled "carbunkel", a magical creature reported in the Americas by early Spanish. They are described as small creatures, with a certain gem on their foreheads. The gems come from the brains of dragons. According to myth, dragons have inside their brain a liquid that crystallizes into a solid gem when they die. According to superstition, it is good luck to catch a carbuncle.
It is safe to assume that the name Carbuncle comes from the latin Carbuncŭlus, which means ruby.
In the tropical America, there is an insect called Carbúnculo, most popularly known as Carbunclo or Cocuyo (dusk star). It is a coleopteran insect; its body is about three centimeters long, oblong shaped, brown and with two yellowish spots to the sides of the thorax, from which it emanates a very bright azure light.
"Vana'diel is the world in which you live. You should see the true Vana'diel with your own eyes." "I will extend a bridge...between the people of the present, and beings of ages past."
--Carbuncle, during I Can Hear a Rainbow