The Rare Chest is a module chest introduced in the 16.2.0 update.
It appears to be a white chest with two blue vertical lines and two brown locks on it. There is a black rectangle on its front side and two tool icons on its top side.
It is opened for receiving rewards, which are modules and coins.
The opening of this chest requires 6 hours in order to fully unlock, but this can be sped up to instantly unlock it by spending . Once fully unlocked, the rewards will be given to the player. In the 16.8.0 update, a new option of skipping an hour is possible by watching an advertisement-based video.
The rewards are: