Red Coin

Red Coins were first seen in Super Mario World 2: Yoshi's Island. In which, they were hidden in Gold Coins. The only way to tell which coin was which was to grab it and see or use a Magnifying Lens. There were twenty coins in each level, and counted as twenty points for your score at the end of the level.

They were later see again in Super Mario 64. In which one was worth two Gold Coins. Collecting all eight in one course would make a Power Star appear over a Star Marker.

They made another appearance in Super Mario Sunshine. This time, collecting all eight would make a Shine Sprite appear.