From behind, one can see a view of SpongeBob's "brain", with Plankton controlling him, which was inspired by the SpongeBob episode "Plankton!", in which Plankton takes over SpongeBob's brain. This area contains various gears and consoles, with the gears providing interactivity.
This is a description taken from LEGO.com. Do not modify it.
Plankton on the brain!
Just when you thought things couldn't get any wackier in Bikini Bottom'¦Plankton has taken over SpongeBob's brain and is making him do some wild things! Plankton can make SpongeBob spin his eyes, shoot jellyfish from his mouth, and change SpongeBob's expression from a frown to a smile. Set includes Plankton minifigure, jellyfish to shoot and much more! SpongeBob measures over 11.5 inches (29.2 cm) tall! Includes SpongeBob comic strip on the box!