Dragon Fossil

The Dragon Fossil is located in the Fossil Room of Cloud Tower. This was used as the vessel for the Trix's collection of magic from mystic schools.

Overview
This dragon fossil was also the source of the Trix's power-up crystals. The dragon would store the stolen magic and the stored magic would be used to give abilities or amplify power. The Trix had used it for themselves and their proteges, the Cloud Tower Elites.

Appearance
Based on the appearance of the fossil, the dragon was a massive creature with wings.

Season 6
The Trix uses this fossil as a conduit for the stolen magic they have collect to increase their powers. This grants them the power-up crystals. Upon the crystals being destroyed, the power is returned to the fossil.

Selina walks in front of the fossil, irritated at the Trix for refusing to share their power. She vents to Acheron who also shares the same feelings. He provides a suggestion: make the Trix enter the Legendarium World and trap them there.

The fossil is present during a "class lesson" for the Cloud Tower Elites. The Trix ask their proteges what is the most important aspect of a witch. Zulema answers correctly, "power." The Trix then bestow them intangibility using the fossil.

It remains untouched though still containing stolen magic until Selina, who had a revelation and realized she was wrong, destroys the fossil, releasing the stolen magic. Thus, returning the magic to the respective schools.

Trivia

 * In "The Anthem", the fossil is missing its body.