Kelp Nougat Crunch is a food that only appears in the episode "Rock Bottom." SpongeBob tries to purchase it from a Rock Bottom KANDY machine because he gets hungry while waiting for the bus back to Bikini Bottom.
"Kelp Nougat Crunch" appears to be a small candy bar that has a red wrapper with a white banner on the wrapper. It has "Kelp" written in the center in light/electric blue. Rock Bottom KANDY machine. Kelp Nougat Crunch resembles the wrapper and appearance of a mini Snickers or mini chocolate, possibly a Kit-Kat or Twix.
After waiting for the bus to get from Rock Bottom back to, SpongeBob eventually grew hungry. He first ate candy from his "Glove Candy Dispenser" he got from Glove World, but he spat them out due to them being "Glove Flavored."
He then notices the snack machine across the street and goes toward it to get some candy, but everytime he does, the bus leaves. SpongeBob eventually tries to trick the bus by not getting the candy bar, but fails, and one of the local Rock Bottomites takes SpongeBob's "Kelp Nougat Crunch." As the Rock Bottomite runs away, SpongeBob shouts, "Hey, that was mine!" at him.