It is a sand tank has two sets of five wheels on both sides of the tank with belts over them. On top of the structure is a window and a shooting device. The entire tank is a sand color with traces of bolts and pieces seen on a real tank.
Role in episode
The sand tank appears as SpongeBob and Patrick are fighting at the beach. SpongeBob uses the tank to protect his base, as well as an offensive maneuver against Patrick.