Scorpius is a gigantic robot scorpion, with Robotnik's face as its head. Once Sonic collects the three Chaos Emeralds within the caverns, the room to Scorpius opens and Sonic can battle against the mechanical scorpion.
Scorpius has an extendible tail, which it can use as a shield and drip poisonous liquid from the tip. Sonic must jump into the gap between the tail and the body in order to attack the body from within; if he succeeds, he will bounce repeatedly within Scorpius and cause significant damage, unless he slips out of the gap, and therefore must reenter. After a certain number of hits, the tail will break off and Sonic can attack Scorpius' body directly, with another certain amounts of hits will destroy Scorpius. An alternate method of destroying Scorpius is by hitting the four switches on the ceiling, causing a landslide that will crush the robot.
During the battle, if Sonic falls to the bottom, he will be shot back up, so he cannot leave the room until Scorpius is defeated.