The Raw Sewage burger looks similar to a Krabby Patty except it is darker in color. It also has dark green sauce on it that resembles raw sewage. The ingredients look much more decayed and the patty contains a strange odor.
Role in episode
SpongeBob thinks that Plankton stole the secret ingredient for the Krabby Patty until he finds out that the burger is not a real Krabby Patty and just a failed duplicate attempt. Plankton explains that he is going through every single ingredient there is to try and duplicate a Krabby Patty, and that he is on the R's and Raw Sewage is his latest attempt.