While a group of enthusiasts were going through the game's files, they noticed that they were able to find the sprite sheets were just off frame for each of the game's zones, appearing when triggered. When they got to the Krusty Krab's sheet, this character appeared among the other stored object of the environment. Two separate frames for this character were discovered, the one with the face in view ("Yummer 2") and just the hands ("Yummer 1") which appears in a separate part of the location. After many emails were sent to the development team, they finally came out with some official statements about the origins of this character. Yum is a modeling test that was created around the year 2010. He had become a meme around the office. They used this character as a placeholder, as it was recognizable when going back and editing work. In addition to this, they explored what this character would look like peaking around poles as Mrs. Puff and Mr. Krabs. They forgot to remove him, and thus the character's model still remains on the game's atlas.
Credits https://gaming-urban-legends.fandom.com/wiki/Yummer
