Bells are the currency featured throughout the Animal Crossing series, introduced in the Nintendo 64 title Doubutsu no Mori. Their appearance is very similar to that of coins from the Mario series, specifically those from Super Mario 64.
They appear in the Animal Crossing course featured in the Mario Kart 8 DLC pack Animal Crossing × Mario Kart 8, which returns in the base game of Mario Kart 8 Deluxe. They replace coins from other courses, being both scattered throughout the course and obtainable from Item Boxes. They function identically to coins, giving a greater speed boost to players the more of them they have. The bottom left display which normally shows a coin next to the counter instead displays a round bag with a star on it; this is the most common appearance bells take in the Animal Crossing series.