Obstacles

Summary

 * Obstacles are plants and rocks that are randomly placed in your village. You start with about 40 obstacles around your village. You can remove them if you have an available Builder and a small amount of Gold or Elixir. Gold is used to remove rocks and Elixir to remove vegetation.
 * Each obstacle that is removed will yield 0, 1, 2, 3, 4, 5, or 6 Gems.  The distribution is not random and follows the following repeating sequence: 6, 0, 4, 5, 1, 3, 2, 0, 0, 5, 1, 0, 3, 4, 0, 0, 5, 0, 1, 0. This means on average, each obstacle cleared yields 2 Gems.
 * Supercell changes gems yielding pattern. Above pattern has been changed to this sequence: 3, 2, 0, 0, 5, 1, 0, 3, 4, 0, 0, 5, 0, 1, 0, 6, 4, 5, 1. Clearing every 20 obstacles gives you 39 gems. This pattern does not include 25 gems yielded from Gembox.
 * Vegetation respawns at a rate of one item per eight hours, except if all the spaces in your village are totally filled. Furthermore, an obstacle will only spawn if there is a one tile buffer zone between the spaces in which it will spawn and another building or obstacle.
 * Rocks do not respawn once they are removed.
 * Since vegetation respawns, and removing one may yield Gems, removing vegetation regularly can be an unlimited (albeit slow) source of Gems. This could be a good idea to farm Gems.


 * Your village can have a maximum of 40 obstacles at one time.


 * There is an achievement called "Nice and Tidy" which gives players Experience and Gems for removing 10/50/500 obstacles.


 * Troops can be spawned beside and/or on top of obstacles.

Vegetation
When the game respawns an obstacle, the respawn weight represents the chance of that particular item being the one that appears. Also, a new obstacle called the Gem Box was added, but quickly deleted due to a few glitches relating to how many Gems it gives. They have been added back into the game on April 9, 2014, the update that added Clan Wars.

Rocks
Rocks, once removed, do not reappear.

Tombstones
Tombstones spawn when attacking Troops are killed.

Gem Box
The Gem Box is a mysterious box packed with gems! You can only have 1 gem box at any time in a village. Clearing the Gem Box costs 1,000 Elixir, takes 30 seconds to clear and will give you 25 gems. The gem box is rare but in the recent update they made them more common.

Special Obstacles
During the Winter 2012 Update, they added a X-mas Tree that gives 30,000 Gold when cleared, which was then increased to 50,000. On 3 January 2013, Supercell indicated on the forums that people will get to keep their trees even after the winter theme is gone.

During the Winter 2013 Update, they introduced another X-mas Tree that gives 75,000 Gold when cleared.

Video of X-mas tree (2012) being chopped down and the reward: http://www.youtube.com/watch?v=3YC0GPHflwQ

Undecorated Obstacles
