Bubble ring

A bubble ring, also known as a Water Ring or simply a ring, is an underwater object appearing in Super Mario 64 and its remake, Super Mario 64 DS.

Super Mario 64 / Super Mario 64 DS
In Super Mario 64 and Super Mario 64 DS, bubble rings are seen only in the ninth course, Dire, Dire Docks. When Mario swims through a bubble ring, it will replenish two wedges of his Power Meter, and a number will appear above him. This number represents the number of bubble rings Mario has passed through. When Mario swims through five bubble rings, he will be granted a Power Star.

Bubble rings are required for the fourth and fifth Stars in Dire, Dire Docks. In the fourth mission, Through the Jet Stream, Mario must swim to the other side of the tunnel to find a jet stream spraying out bubble rings. After Mario collects five of these bubble rings, a Power Star appears above the jet stream that Metal Mario can collect. In the fifth mission, The Manta Ray's Reward, Mario will find a Manta Ray swimming around underwater and leaving a trail of bubble rings. Mario must follow this trail to collect five bubble rings and make the Power Star appear.

Mario Party 4
In the Mario Party 4 minigame Manta Rings, rings appear along with a gold type created by a Manta. The blue rings are worth one point, and the gold rings are worth three points. In this appearance, the rings are composed of bubbles.