The Compass symbol is the one which acts as a mystery position (Transformation symbol), getting turned into regular symbols of the same type, wherever it may appear during a spin. If appearing in free spins mode, it becomes sticky and gets to help out over the course of several rounds. Treasure Chest scatters do show up as well, and they are going to be the triggers for a free spins feature. With three scatters, the game gives you 10 free spins. The extra bit of profitability of this feature appears to come from the sticky mystery symbols, which I’ve mentioned above. The reels which get the Treasure Chests are the 1st, 3rd and 5th ones.