Transmetals is a subline of Beast Wars featuring toys with mechanical animal modes and organic robot modes. The subline was released in conjunction with Beast Wars
In the fiction, Transmetal technology is an adaptation accidentally discovered by the Beast Wars era Transformers. During a transwarp explosion which claimed the life of Optimus Primal, a "quantum surge" was created which had several repercussions for the Beast Wars. Rattrap, Cheetor, the reincarnated Optimus Primal, Tarantulas, and Megatron were all changed by the wave into the first generation of Transmetals. Rampage and Depth Charge also became subjected to this, and several expanded universe Transformers also underwent the process.
The Transmetal technology allows the Transformers to withstand and actually absorb raw Energon radiation and exist in a non-beast mode in these environments without issue. In addition, Transmetals can utilize a "vehicle" mode, such as wheeled (Rattrap, Tarantulas) or flight (Megatron, Cheetor, Primal). Although not explicitly stated in the cartoons or comics, it's hinted at in the toy series' tech specs that the quantum surge Transmetalization process essentially turned the Transformers 'inside out', making their alt modes the one that is largely mechanical, instead of the other way around as normal. Transmetal 2 technology blur the lines between which mode has the technological and which has the organic, making them partially techno-organic, though far less refined than the process used in Beast Machines.
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