Mechanimal

The planet Cybertron is home to more than just Transformers. Throughout the multiverse living Cybertronic fauna of many varieties fill its metal ecosystems. Dubbed mechanimals, these beasts fill many of the same niches (and take many similar shapes) as flesh and bone animals on Earth and other organic planets.

Interestingly, though they can be wild or tamed as with organic animals, mechanimals, due to their mechanical nature can also be easily upgraded, altered, or even granted sentience.

Fiction

Beast Wars: Uprising

The mechanimals had nearly been rendered extinct by the millennia upon millennia of war that had torn Cybertron. It wasn't until Thunderwing inadvertently returned the Underbase to Cybertron that mechanimals began returning, blooming while the rest of Cybertron suffered. The Builders, as was pretty typical of them, saw the ever-increasing animal population just as an infestation. Derailment

Over the next four centuries, the mechanimals only went from strength to strength.

Four cycles into the Grand Uprising, Megatron noticed mechanimals could metabolise their own energon. It was this that inspired him to implement the Beast Upgrade, wherein all Maximals and Predacons would take on far more efficient beast modes based on mechanimals. Not All Megatrons