Junior is an adorable baby scallop who was raised by SpongeBob and Patrick in the episode "Rock-a-Bye Bivalve." Since Junior had no family to take care of him and was alone, SpongeBob and Patrick become the adopted parents. He eventually learns to fly at the end of the episode.
Junior apparently hates Krabby Patties, making him one of the few characters that does not like them. He also dislikes donuts and french fries. Instead, he likes to eat worms and ice cream with worms. He also needs to have his diaper changed very often. Junior also makes similar crying sounds of a young baby very frequently throughout the episode. Junior, at the end of "Rock-a-Bye Bivalve," then leaps out of SpongeBob's window, and begins to fly, thus, making it the last time we see Junior ever.
Junior looks like any other scallop; he has a purple shell and has a red tongue.
People have theories that he may return.
Though uncomfirmed, it's possible that he might be old Bluelip (as people say).
Despite being adopted, he is Patrick's son meaning he is Royalty and the prince of the Star family.
He might be the clam in the cage in SpongeBob's bedroom.