Heart Fruits can be found within the floating bubbles which can be popped. Heart Fruits also spawn if a Yoshi eats 6 Melons in a row. Eating a Heart Fruit will transform Yoshi into Super Happy Yoshi. Not only this, when he is in one of the areas of Poochy and Nippy, the snowflakes will fall.
The Heart Fruit is a large, heart shaped red-fruit with a smiley face on it with a small green stem extending from the top of the fruit.