Carbuncle
Carbuncle is a bunny/fox-esque companion summoned by Arcanist and Summoner. Arcanist and Summoner can spawn their pets with the actions 
Summon Carbuncle, 
Summon Ruby, 
Summon Topaz, and 
Summon Emerald. Each type has a different attack focus, either single-target or area-of-effect.
Additional Information
Carbuncle is also a server in the Japanese Elemental Data Center.
Lore
“Using geometric symbols to lend shape to living aether, certain mages can unlock the latent power within certain gemstones-a power which can be directed to the "summoning" of aetherial beings known as Carbuncles. The inherent traits displayed by these familiars differ depending on the stone used in their creation- emerald and topaz being the most common, with ruby and diamond also proving popular.
— Encyclopædia Eorzea vol 1, page 301