Clash of Clans Gem Box is the most wanted Obstacle. In game, it is a small wooden box with plenty of gems inside. Because of those rare gems, there are a lot of twinkling stars around the box. There is also a rainbow above to connect it with the sky. It is as a small gift the developer team send to all players to help you play easier.
You need to spend 1000 Elixir and 30 seconds to remove it. After removing the Gem Box, you will receive 25 Gems. That’s why every player want to see it everyday! (I have seen some (just some) players have just 20 Gems after opening the box, I really have no ideas about this, maybe it is just a glitch.
You can just have a Gem Box at a time. Although it is very rare but normally you can see it every 1-2 weeks. So whenever you see it on your ground, remove it as soon as possible so the next one can be out sooner and always make sure that it has enough space on your land to respawn.
25 Gems is not a big number (boosting all Barracks takes up to 40) but a long with removing obstacles in game (trees, trunks, mushrooms,…), you can earn up to hundreds every week. After a few months, you can finish the 5th builder, one of the main goal of all players in game.
And the last one, the enemy can’t steal it from you! Sometimes I even see players using Lightning Spells to zap it. LOL.