You can use the harpoon to destroy one layer of any obstacle, or any destroy any colored item. This won’t use up a move.  

 

Use the harpoon by tapping on it – it’s on the bottom right of your match-three screen! When you’ve tapped on it, tap on any obstacle or item to destroy with the harpoon!  

 

If you’ve tapped on the harpoon but don’t want to use it, tap again outside of the match-three area.