Plankton's size changes throughout the episode. When he is first seen, a magnifying glass is required to see him clearly. When he encounters SpongeBob, he's about the size of SpongeBob's finger. When he snakes into SpongeBob's brain, he's about the size of a walnut. Then, when he jumps to the Krabby Patty, he's the size of SpongeBob's finger again.