Star Fragments

Benefits
Once you get to 10 stars, you will be able to make Star Fragments. You can use Star Fragments to level up your Stars, increasing their multiplier.

To do that, you will have to convert barrels. The higher level the barrel, the more Star Fragments it gives you. The amount of Star Fragments given can be increased through the 'More Fragments' upgrade, purchasable with Bricks.

Tricks
The most efficient way of getting Star Fragments is to activate a x10 Faster Barrels power up, and just keep on tapping the barrel above which the confirmation window's yes button appears.