Quarry 7 is a pretty straightforward level.
- Merge the 3 Grass Dragon Eggs
WARNING: Dragons will automatically attack the Lifeless Stone - if they destroy it automatically, it will not count towards the Goal Star. Also, double-tapping to destroy lifeless stones does not count toward the quest the way that it does for harvest quests. You actually have to grab the dragon and drop him on the stones 12 times. This is why you should only create one dragon initially.
- Drop the Grass Dragon Welps on Lifeless Stone 12 times. (Goal Star)
- Merge the 5 Spotted Dragon Eggs (Goal Star)
- Merge Fresh Stone to get Moss Covered Stone
- Merge Moss Covered Stone to get Living Stone x 3 (Goal Star)
- Merge Living Stone to get Large Moss Stone (End Goal)
For the purposes of the goal star, you don't have to wait for the dragon to finish destroying the stone it's working on. You can grab the dragon again and drop it on the same stone multiple times.