Not sure why I'm bringing this up but a while ago I noticed something odd. Plankton does not have that many appearances in the first 3 seasons. Looking back he only appeared in I'd say around 5 or so episodes on average per each season. Usually when he did appear the plot was either centered on him (usually trying to steal the formula) or he just appeared in a very minor role. In later seasons it seems as though he appears far more. I'd say in nearly half the episodes per season. On top of that he seems to fill more versatile roles in these later seasons too. It's just so odd because it always felt like he was far more integral to the first 3 seasons than maybe he actually was.