Stars show you've completed a Daily Challenge skillfully. If you get enough, you will unlock a Lifetime Zoo Tile!

There is also one unique Zoo Tile available each month. To earn it for the month, you will need to earn the number of Stars required.

The Zoo Tiles that you have unlocked will appear at the bottom of the Zoo Tiles area and you can tap on them to learn a fun fact about the depicted animal!

The amount of Coins you receive from completing the Daily Challenge is the same no matter how many Stars you get. There is also no additional Coin bonus received from unlocking a Zoo Tile.