In the 2007 live-action film Transformers, Autobots en route to Earth change their alternate modes into structures resembling solid comets or burning meteorites for space travel (a possible homage to the stasis pods plot device from Beast Wars). Once they arrive, they will transform into an equally detailed yet generic & undefined robot mode to allow them more stable ground mobility in order to search for an adaptable disguised form (aka vehicle mode); upon which scanning and replication are initiated and completed within seconds, giving them their now-unique physical characteristics. These near-identical transformable skeleton-like forms are referred to by fans as "protoforms" due to their generally similar appearance and function to the Beast Wars versions, though they are not specifically named such in the film. Also, a protoform retains the same mass as the final appearance of a Cybertronian with a chosen vehicle mode after scanning & replication are complete, so one protoform can be larger and/or smaller than another. Whether-or-not a protoform has [usable] weapons is not shown or mentioned of in the film. In theTransformers: Movie Prequel book, protoforms are the base forms for all transformers on Cybertron, hence their skeletal look; all armor, weapons, sensors, transformation, etc. are integrated into this later when landfall is made. (Bumblebee is portrayed on Cybertron as a protoform and later in the book Starscream, Barricade, and Blackout are seen as protoforms on Mars). It should also be noted that a Transformer can apparently turn into a protoform as much as it needs to. Bumblebee first landed on Mars and then went to Earth after finding a Mars rover, evidencing the theory.
Much unlike those in Beast Wars, protoforms in the live-action film are shown to be extremely tough and durable, obviously withstanding theatmospheric reentry and hard landing as they arrive on Earth, as said by the Transformers Movie Guide; whereas in Beast Wars, protoforms (see above) are portrayed as fragile and delicate.
The toys of protoforms of Optimus Prime and Starscream were available for sale before their normal Earth forms were; this is the first time a protoform of any kind was available as a toy.
