SpongeBob is a sea sponge who appears in the episode "SB-129" and briefly in a clip at the end of "Ugh." He is SpongeBob SquarePants' prehistoric ancestor and has the same name as him.
He is a yellow square-shaped sponge who has a large sloping forehead and a large ape-like mouth with a notable overbite, and his teeth are large and thick. He wears a loin cloth that can be replaced upon tearing.
Role in series
He is revealed when Squidward attempts to find a quiet place to play his clarinet. At first, the meeting between the two is awkward yet calm; he even sniffs and plays with Squidward's arm out of curiosity.
When a jellyfish swims by, he becomes afraid of it and runs away, screaming with Patrick, who also has the same name as his descendant. He is later seen holding a jellyfish and being continuously stung by it, screaming and passing it to him. Squidward becomes annoyed at their screams and tells them they are supposed to catch the jellyfish, not torture themselves with it. They do not understand so Squidward takes a stick and loincloth from both primitives, crafts two loincloth jellyfish nets, and shows them how it works.
Both primitives enjoy the game and take the nets to run after the escaping jellyfish while Squidward goes back to his clarinet playing. This, however, proves to be a bad decision, as neither primitive finds the sound very pleasant and they angrily pound their chest and chase Squidward back to the time machine.
Willingly getting stung by a jellyfish (witnessed by Squidward)
Jellyfishing (caused and created by Squidward)
Destroying sources of annoying/high-pitched sound (case in point, Squidward's clarinet)
He is not very smart. He cannot talk like the Bikini Bottom citizens of today. Instead, he communicates by growls and whimpers. His high tolerance for pain is what keeps him holding onto the angry jelly and repeatedly getting stung. He could understand Squidward's demand for his loincloth. He also looks very crazy when noticing Squidward.