He is a sea sponge who looks very similar to SpongeBob. The only major differences are that his teeth are more spread apart and his clothing; SpongeBuck wears a red bow tie, a black bowler hat with a bell, a striped square shirt, and a pocket watch (tucked into his pocket; the chain hangs loose). SpongeBuck was fairly easy to please and he loved to Spurskate.
He was born to an unknown Mr. and Mrs. SquarePants and outside of the area now known as Bikini Bottom. He is the only known SquarePants family member to not be born in the area now known as Bikini Bottom. This means sometime between SpongeGar and SpongeBuck, the SquarePants family moved out of the area.
At some point in his life, he learned how to make chili, which was terrible according to William Krabs.
When he was an adult, he hopped on a train and took off to a town known as Dead Eye Gulch.
When he got there, he went to the Krusty Kantina, a bar, and asked for a job. He was given a job, but not the job he was hoping for. He was given the job as sheriff; he wanted the fry cook job.
Soon, he met another important person, the founder and ruler of Dead Eye Gulch, Dead Eye Plankton. He was a mean creature who wanted the Krusty Kantina (the only place he didn't own). When Dead Eye met SpongeBuck, he ran him out of town.
After having a prep talk from Pecos Patrick, SpongeBuck decided to go back and fight. So, at high noon, he fought Dead Eye and won by squashing him. (which none of the townspeople had thought of).
Later, the townspeople made a statue of SpongeBuck out of all of Dead Eye Plankton's gold. SpongeBuck was also given the fry cook job.
In the present, his grandson would clean the statue of him and would be amazed at his grandfather's actions, just as SpongeBuck predicted. SpongeBob apologized to it for not recognizing him earlier and decided that he had to make himself known, as he had a lot to live up to.
His accent is slightly different from SpongeBob's.