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A structure is a term used to define the body of a Transformer. Without a spark or a personality component, the structure is a lifeless shell. The superstructure is the outer portion of the structure, generally containing components for the transformer's alternate mode, and is often changed during reformatting in accordance with disguise protocols. The substructure contains a transformer's inner workings, and usually includes any special equipment or weapon systems.

At times, the spark-less bodies of deactivated Maximals have been referred to as shells.

A Transformer's structure varied depending on which form their personality inhabited. The Renegade Decepticons when freed by Starscream developed new structures when their personality components were placed in Earth vehicles.

Fiction

The Transformers cartoon

After being captured, the Renegade Decepticons had their personality components removed from their structures which were destroyed. Starscream's Brigade

Beast Wars cartoon

After the Planet Buster had been destroyed, a quantum surge followed in its aftermath. When the surge hit Earth, several Maximals and Predacons were struck by its impact and their superstructures mutated into their Transmetal forms. Aftermath

Later, when Megatron began experimenting with an alien device to create a new form of Transmetal, Cheetor was caught in the experiment and had his superstructure once again mutated into his Transmetal 2 form. Feral Scream Part 1 Feral Scream Part 2 Blackarachnia attempted to achieve the same result on herself, which was strugglingly met with success. Crossing the Rubicon

Beast Machines cartoon

While exploring Cybertron in the wake of Megatron's conquest, Primal's team of Maximals came across an entire facility stacked with deactivated Maximal bodies, which (playing on both "graveyard" or "junk yard") they later referred to as the "shell yard". Spark of Darkness