Junior looks like any other scallop; he has a purple shell and a red tongue.
Junior apparently hates Krabby Patties, even the tiny variety which are catered to babies like him, making him one of the few characters who dislikes 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 makes similar crying sounds to a young baby very frequently throughout the episode.
Role in episode
Junior is found by SpongeBob and Patrick in a bush. SpongeBob discovers that Junior is still a baby and cannot fly. Since Junior has no family to take care of him, SpongeBob and Patrick become his adoptive "parents." He is mostly tended to by SpongeBob while the irresponsible Patrick neglects this.
This frustrates SpongeBob to no end, eventually leading up to an argument between them. However, they cease arguing after seeing Junior standing in a window and try to save him but do not make it. They get sad at failing Junior but discover he has learned to fly at the end of the episode. Junior thanks SpongeBob for caring for him with a kiss, while he drops a coconut on Patrick's head but kisses him too and they watch Junior leave in adoration.
Patrick almost killed Junior by threatening to step on him as a solution to dealing with his helplessness, before SpongeBob talks him out of it.