Sheldon J. Plankton, more commonly known as Mr. Plankton, is the owner of the Krusty Krab in "The Algae's Always Greener." He never appears, but Plankton is mistakenly called "Mr. Plankton" throughout the episode.
He looks identical to Plankton except, he wears the same style of clothes as Main Universe Mr. Krabs.
This section has speculative information. Please keep this in mind as you read it.
Most of his life events are likely the same as Plankton up to the point when he and Mr. Krabs lost their friendship.
It is is possible that in this universe, Mr. Krabs and Plankton where in the reverse places inside their restaurant. This means that Mr. Krabs went flying out the door, gaining only "chum" as part of the recipe and Plankton hit the wall making the ingredients on the shelf fall, making the Krabby Patty. His success would lead to him leaving Karen for the female that Main Universe
Mr. Krabs marries. Mr. Plankton and this female have Pearl Plankton. Mr. Plankton then hires the exact same people as main universe Mr. Krabs to get him where he is today.
He is mentioned and referred to by numerous characters because they think that Plankton is him.
His only known family is his daughter, Pearl Plankton.
He runs the Krusty Krab.
It is possible that technically, the main universe Plankton also switched lives with the Actual Mr. Plankton meaning that Plankton and Mr. Plankton have also switched souls making the actual Mr. Plankton getting the Main Universe Plankton's Body in the Main Universe for a while since there was a picture of Mr. Plankton and Alternate Universe Pearl as a memory, for example.