Shiny Bubble is the son of Bubble Buddy. He does not seem to talk much and is rather small. He was left with SpongeBob SquarePants to be looked after, as his father was running errands.
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 resulted in SpongeBob chasing after him in attempts to save him from being popped by hazardous objects.
Shiny resembles his father, only much smaller, and he wears a bubble baseball cap with a collar. Shiny is also described as a mischievous character who causes trouble to everyone around him, just like his father, Bubble Buddy did. At the end of his debut episode, he also blows a raspberry at SpongeBob. It is unknown who his mother is, though.
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.
Figuratively speaking, Shiny is SpongeBob's grandson because SpongeBob created Bubble Buddy and Shiny is Bubble Buddy's son.