Cerebro-shell

Cerebro-shells are devices used by the Decepticon Bombshell. They have the power to control the minds of both humans and Transformers if injected into their brains.

Pre-MUX continuity
When Bombshell and Dirge were ordered to take control of Power Station Alpha, they discovered Bumblebee watching it on behalf of the Autobots. To distract him, Bombshell fired a cerebro-shell into young Anthony Duranti and ordered him to stand in front of the station's tracks during launch. Bumblebee was forced to transform and rescue him, which led to him being shot and injured by G.I. Joe for being a giant robot.

Bombshell then infiltrated Power Station Alpha and planted a special cerebro-shell in its mainframe, which let Shockwave control it back to the Decepticon base. However, Doctor Mindbender of Cobra managed to lock onto the shell's electronic frequency and control the station over to the Cobra base instead. Meanwhile, Anthony, whom Bombshell apparently forgot about after he served his purpose, had become completely unresponsive, so his mother took him to a doctor, who spotted the cerebro-shell via x-ray.

The shell was surgically removed by Doctor McGrath and Duranti returned to normal, while McGrath started prodding the shell while trying to figure out exactly what it was. This caused Bombshell to spasm and transform out of his own control back at Decepticon headquarters, although he only suspected some generic circuit malfunctions.

The shell eventually ended up in the hands of Mainframe of G.I. Joe, whom also started prodding it. The deactivated Bombshell, who'd been brought into the very same room as the shell by Doctor Mindbender, started spasming again, and everyone found this very interesting.

''In an attempt to ruin the Autobots' reputation amongst humans, Bombshell later injected Superion with a cerebro-shell, forcing the massive combiner to rampage through New York City. However, the Autobots recruited a reporter by the name of Irwin Spoon to climb inside Superion and remove the shell.''

Unfortunately, Irwin never got a chance to share this experience with the world, as Bombshell simply injected him with another cerebro-shell and made him write mudslinging stories about the Autobots instead.

After being caught in a battle of misunderstanding between the Insecticons and Megatron's Decepticons, Mirage was left sitting unconscious in a wasteland, where the Insecticons found him. Bombshell implanted a cerebro-shell in him, effectively turning Mirage into a slave to use against the other Decepticons (whom the Insecticons considered enemies at the time, due to the aforementioned misunderstanding). When the two groups settled their differences, Megatron used Mirage to lead the Autobots into a trap. Cliffjumper punched the traitor's lights out in the ensuing battle, and Ratchet found and removed the cerebro-shell when examining him afterwards.

The Insecticons later devoured the Nova Power Core, which greatly increased their size and power. They decided that with this power, they didn't need to remain with Megatron anymore, and when Soundwave overheard their conversation, he was spotted and injected with a cerebro-shell. The Insecticons still followed Megatron to Iron Mountain, where they revealed the next part of their plan and fired cerebro-shells at Megatron and the Seekers. The latter group fell victim to Bombshell, but Megatron managed to grab and crush the shell fired at him, causing Bombshell to cry out in pain. After the Insecticons lost the power of the Nova Power Core, Bombshell lost control of Soundwave and the Seekers, and their shells were ejected. He then used a "special" cerebro-shell to re-assemble Shrapnel, who had been blown to pieces.