Gold Ring

Gold Rings are objects that appear in New Super Mario Bros. 2. They are similar in appearance to the Coin Rings from Super Mario 3D Land. If Mario or Luigi passes through one of these, some enemies will turn golden. In this state, five coins are given for each defeated enemy. If multiple enemies are defeated consecutively (either by stomping on them without touching the ground or using a Koopa Troopa shell), the number of coins earned is increased by 5 for each consecutive enemy (i.e. 10, 15, 20, and so on). Additionally, while in their golden form, most enemies leave trails of coins behind as they move, or even throw coins instead of their usual projectiles.

Trivia

 * In the E3 trailer of New Super Mario Bros. 2, when the enemies were in their golden forms, it was shown that only five coins were given for each enemy defeated in succession (using the golden Koopa shell) instead of having the amount increasing by five for every consecutive enemy.
 * If Mario/Luigi goes through a gold ring the game screen will twinkle.