Box of Dead People, also known as Loot Box, is a feature that was added in the Chrono Quests update.
When a player dies, this box will appear in their place. Other players can destroy this box and receive some items that player who died has own. However, the time to get these items are limited. After about three minutes, the box will disappear.
To do the first three chrono quests, players cannot use boxes to their advantage. Doing so will fail the quest.