They are rings that are normally yellow, but turn red if missed.
Role in game
When the guitar missile goes through the rings on time, another one will appear until the target has been reached. When a ring is missed, the ring turns red and then disappears, causing the task or mission to fail or be sent back to the checkpoint for slide levels. They are also served on ring challenges for driving and sliding challenges.
Most of the levels they appear in are where SpongeBob performs the Sonic Wave Guitar challenges after being granted the power by Princess Mindy. To access said challenges, the player must make SpongeBob stand on a wooden floor with a starfish painted on it and then proceed to start. All of the levels where the guitar challenge is included are where Patrick is the main playable character. They also appear during the challenges of the driving and slide levels.
The following is a list of levels in which they appear in:
"I'm Ready, Depression"
"Sandwich Driving 101"
"Rub a Dub Dub Slip Slide in the Tub"
"Bubble Blowing Baby Hunt"
"No Weenie Parking Any Time"
"Shell City, Dead Ahead"
"Googly-Eyes and Smelly Knick-Knacks"
"Drive of the Knucklehead McSpazatron"
Even though SpongeBob is the one who can play the Sonic Wave Guitar challenges, there is for some reason a painting of a starfish on the platform he must stand on to proceed to the challenge.