The Chocolate Bar has had 2 different looks. In "Chocolate with Nuts," it is a fat rectangle shape (almost a square) and it is deep purple with thin goldish-yellow sides. It has a red diagonal line going from the bottom left corner to the top right corner. In "Life of Crime," it is still a rectangle, but skinnier and longer, it is brown, and says, "CANDY" in reddish-pinkish all capital letters.
Role in the series
"Chocolate With Nuts"
For the entire episode, SpongeBob and Patrick decided to sell chocolate bars in order to start living the fancy life. In the beginning, they didn't do so well as they were constantly being chased by a crazed Tom yelling "CHOCOLATE!!!" and being conned by a fish (SpongeBob and Patrick didn't or still didn't know that they were being conned the entire time). SpongeBob finally gets an idea to sell chocolate by "stretching the truth." This works out to much success as they managed to sell many bars of chocolate to most of the people of Bikini Bottom. However, they end up being conned by the Con Man after he faked being in a full body cast. When SpongeBob and Patrick looked like they were going to give up, Tom appears again and scares them. However, he ends up buying all of SpongeBob and Patrick's chocolate with a huge stack of money and the duo can finally start living the fancy life. They end up buying a fancy restaurant and goes on a date with two much older fish.
"Life of Crime"
Chocolate bars make a small appearance in this episode but plays a major role for the climax. After Patrick thought they were going to starve, SpongeBob takes out two chocolate bars for them to eat. Patrick ends up eating his chocolate bar but then doesn't know what happened to it. He then accuses SpongeBob of taking his chocolate bar and wants him to give it back. SpongeBob denies trying to tell Patrick that he already ate is but Patrick doesn't budge. SpongeBob even offers to share his chocolate bar but Patrick STILL thinks SpongeBob stole his and wants him to admit he took it. SpongeBob gets fed up with Patrick and finally decides to eat his chocolate bar. He eats it very slowly torturing Patrick and finally finishes the bar. Patrick, furious, then decides to tell on SpongeBob for stealing the balloon earlier in the day, to which, SpongeBob reacts to tell on Patrick for doing the same. They both head into a police station and tell the two policemen what happened. SpongeBob and Patrick only go into jail for a few seconds after the policemen told them they stole the balloon on Free Balloon Day. Also, in "Chocolate with Nuts," he calls it chocolate bars, and in this episode, he calls them rectangles, likely because of its shape.