The casket is the container in which the Goblet of Fire is held.
Overview[]
This casket's sole purpose appears to be containing the Goblet of Fire. It is brought out during the opening ceremony of the Triwizard Tournament, and is the first thing the students see before the Goblet of Fire is unveiled. Presumably, after the Goblet of Fire extinguishes itself, the Goblet is placed within the casket again until the next tournament.