It is a squeaky red toy ball with an air hole. It is made for pets.
Role in series
"Gary's New Toy"
Due to Gary's abnormal and obsessive chewing of every item in SpongeBob's house, the two of them go to the Pet Store to buy a chew toy for Gary, so as to put an end to his habit. They settle with a shiny red ball that Gary eventually develops an obsession with. Gary's love for the ball starts to drive him and SpongeBob apart, as Gary's attention toward SpongeBob increasingly declines in favor of his new toy.
The following morning, SpongeBob catches Gary on the ceiling, chewing the ball. He then tells him to make a choice: the ball or him. Gary chooses the ball, leading SpongeBob to leave his house to go find a new life.
Devastated from what he had done, Gary eventually finds SpongeBob under the bus stop bench and apologizes for his actions, thereby betraying the ball and reconciling with his owner.
At the end of the episode, SpongeBob's house explodes and is set on fire. The red ball suddenly appears, at which Gary hisses.
It is one of the things that Bunny Wunny burns in SpongeBob's house.