Shiny resembles his father, only much smaller, and he wears a bubble baseball cap with a collar.
Like his father, he is very mischievous, and his activities in Bikini Bottom are reminiscent, where the seemingly inanimate bubble inadvertently causes trouble and angers everyone with whom he comes in contact. However, unlike Bubble Buddy, Shiny's seemingly innocently floating could be seen as intentional, and results in SpongeBob chasing after him in attempts to save him from being popped by hazardous objects.
He does not seem to talk much.
Shiny has the ability to sprout two heads. His father, however, corrects this by placing him in a bubble bottle and blowing him back out again. He is also a little resistant to popping against pointy objects.
Role in episode
SpongeBob receives a letter while eating Kelpo in the morning. The letter is sent in a bubble and is from his old friend Bubble Buddy, who asks SpongeBob to babysit his son, Shiny, while he and his wife go out for their second honeymoon. SpongeBob introduces himself to Shiny and then introduces him to Gary.
SpongeBob then takes Shiny to Squidward's house to introduce him to Squidward. Unfortunately, Shiny causes mayhem by floating around dangerous objects in the household. Luckily, SpongeBob catches Shiny before he can get popped.
Afterwards, he takes him to the Krusty Krab, where he floats into Mr. Krabs' office and keeps floating around him. Mr. Krabs is sparkly clean from the bubble soap, so he lets Shiny play in the dirty dishes. Unfortunately, Shiny continues to cause mayhem by making the Krusty Krab's floors slipperly with his soap.
They finally go home and SpongeBob decides to feed him a hot dogin the form of a bubble, which bumps into him and pops. Shiny pops too, much to SpongeBob's horror. When SpongeBob finally blows a new Shiny, he has two heads. Bubble Buddy then comes to SpongeBob's house to pick up Shiny. SpongeBob apolgizes about what happened to Shiny and Bubble Buddy accepts it because it happens to him sometimes.
Bubble Buddy then stores Shiny into a bubble bottle and leaves on a bubble plane with his son. As the two are leaving, Shiny blows a raspberry.
Figuratively speaking, Shiny is SpongeBob's grandson because SpongeBob created Bubble Buddy and Shiny is Bubble Buddy's son.