You see a reward container.
It was created on date and time and will be available until the server save on date.
Location
Inside the corpse of some specific creatures and in the Reward Chest.
Notes
Holds the loot of a specific creature you helped defeat. Contents will depend on your participation while fighting it. A container will also appear inside the Reward Chest if not looted before.
A list of the creatures using this system can be found on the Reward Chest page.
Important: a Reward Container will be deleted 7 days after its creation, so make sure to loot it before that happens.