Yoshi Morph Block

A Yoshi Morph Block is a special kind of item that allows Yoshi to temporarily transform into various vehicles, such as a helicopter, mole tank, submarine, etc. After a short while in these states, Yoshi will revert back to normal. During the  Reemergence of Gemerl , Mario finds and throws one of these to Yoshi, who uses the block to transform himself into a helicopter, allowing him to fly through the air and shoot missiles at Gemerl. However, the powers soon wear off, as Gemerl unleashes a powerful aerial kick that sends Yoshi spiraling to the ground, vulnerable once more.

Trivia

 * In the actual game, "Yoshi's Island," a morph bubble is what allows Yoshi to transform, while the block serves as a checkpoint and a means to revert Yoshi back to normal so that he may proceed with the stage; for some reason, the "Dimension" saga reverses this, so that the block does the transformation instead (perhaps because throwing a bubble would have been a little difficult).