Ruby Carbuncle is a Crystal Beast Monster, and is Jesse's Spirit Partner. When this card is Special Summoned: You can Special Summon as many Crystal Beast cards as possible from your Spell & Trap Card Zone. If this face-up card is destroyed while it is in a Monster Card Zone, you can place it face-up in your Spell & Trap Card Zone as a Continuous Spell Card, instead of the Graveyard.
Ruby Carbuncle seems to get into constant fights with Winged Kuriboh, although it's not clear as to why.
- Ruby will debut along with Jesse in Jaden learns How To Train Your Dragon.
- Jeffrey and Xion are able to see Ruby too. Xion also has a Ruby Carbuncle as her Duel Spirit.
- Courtney is able to see Ruby too.