Silver Moon Ring
From Sonic Retro
Silver Moon Rings[1] (シルバームーンリング)[2] are collectible Ring-like items that appear in sets of five in Sonic Forces.
They also appear in the new Cyber Space levels from Sonic Frontiers added by The Final Horizon Update, having the same function as the previous game.
Overview
When the player has collected all five Red Star Rings in a level, then all of the Number Rings in another playthrough of the level, they will be able to collect Silver Moon Rings in subsequent playthroughs of that level.
Similar to Number Rings, all of the Silver Moon Rings are found in a particular section of a level. They can be collected in any order, but once the first one is collected, the remaining Rings are placed on a timer and must all be collected before the timer expires. If the player runs out of time before collecting all of the Rings in the set, they must restart the stage from a point before collecting them if they wish to try again.
Collecting the Silver Moon Rings serves no benefit other than extra bonus points as well as achievements/trophies in the PlayStation 4, Xbox One and Steam versions of the game.
In Sonic Frontiers they also serve no benefit besides the completion of a mission in the levels.