Checkpoint Ring

A Middle Ring (initially the "Middle-Ring") is a blue ring of light in Super Mario World 2: Yoshi's Island  and Yoshi's Island DS. It appears partway through most stages and serves as a checkpoint of sorts. If a Yoshi dies after passing through one, he can restart at the point of the Middle Ring. Also, passing through a Middle Ring will increase Yoshi's Star Power by ten.

Despite their name, Middle Rings are not always placed in the middle of a stage. Some can be found at the very beginning, or not until near the end. A few stages even have multiple Middle Rings, and there are always a couple before boss fights.