Living metal

The base material from which Transformers are constructed is known by many names, including living metal, protomatter, cyber-matter, sentio metallico, elemental metal, and Transformium. Often depicted as the living stuff of Cybertron itself, it is no ordinary metal, but rather, a living substance all its own, possessing a self-replicating cellular structure and a genetic code that defines and shapes a Transformer's natural alternate mode. This adaptable matter is also capable of being programmed to reconfigure into new shapes and designs, which is what allows a Transformer to change their alternate mode when they desire.

It is entirely possible for a new Transformer body to be built without using this elemental substance, using only regular metals; the resultant being is no less of a "real" Cybertronian, but may face some social stigma in an unenlightened society. In some universes, the infusion of a spark into such a body will actually convert it into living metal.

Fiction

Ask Vector Prime

When questioned on the subject, Vector Prime observed that the various names used across the multiverse to refer to the living metal of Transformers' bodies, including "protomatter," "cyber-matter," and "sentio metallico" were all different names for the same thing (but also noted that an expert might potentially distinguish subtle differences between them based on the differing physical laws of different universes). He was loathe to use the word "Transformium," to refer to it, but only because he feared legal reprisal for infringing on a KSI trademark. In response to further questioning, Vector also explained that, in some universes, the infusion of a spark into a body made with conventional materials could convert the substance of that body into living metal. Ask Vector Prime 08/03/15

Notes

• The term "sentio metallico" was created by writer James Roberts for his unofficial Transformers novel Eugenesis, to refer to the living metallic stuff of Cybertron from which Transformers were birthed in the Generation 2 comic. He would later introduce the term into canon through the IDW comic books, in which it was established to be the substance which makes up protoforms.