In Sweet Bonanza, the bonus round is typically triggered by landing a certain number of Scatter symbols – in this case, the Spiral Lollipop symbols. Usually, hitting four or more Scatter symbols anywhere on the reels will activate the bonus round. The bonus round often includes free spins and might have other features like multipliers, which can significantly increase your potential winnings. Keep an eye on the game's paytable and rules for specific details about triggering and playing the bonus round.