Minecraft Earth:Adventure Crystal

An Adventure Crystal was an item $$ that allowed the player to place a private adventure at any location and invite friends to join the adventure. These Adventure Crystals' purpose was to create adventures without the need for the user to go outside due to the ongoing COVID-19 Pandemic (which eventually became the reason for the game's discontinuation).

Obtaining
An adventure crystal could be obtained from:
 * Chest tappables
 * Adventure Chests
 * Daily login challenges
 * Events

Rarity
Adventure crystals had different rarities:

Rarer crystals generated larger adventures, and contained more valuable loot in the adventure chest. The player's crystal inventory could hold a maximum of three crystals of each type.

Interface
Tapping the crystal icon showed the crystal adventure interface, which showed the crystals collected by the player and their rarity. Tapping a crystal showed the adventure duration, as well as a graphic representation of the size of the adventure and the reward:

History
ja:MCE:アドベンチャークリスタル zh:MCE:冒险水晶