Every now and then you hit a letter bubble that counts as a star in the lower left corner which doesn..

If you find a word that's not part of the puzzle you get a credit for it in the lower left corner. Once its full it will have a glowing light around it, you then tap it and you'll get 35 points. You can tap on it before it glows and see which words qualified. Each time you fill it with non-puzzle words, it will glow, tap on it during a game and you'll get those 35 points, or watch one of those awful videos and double it. Have fun, I love this game!