Not all iterations have life that is easily recognizable. In the early explorations of the infinite variance, intentionally or otherwise, Ben brought a steam-driven cybernetic mechanism into the bridge that has since assimilated and reproduced itself into an entire ecosystem. Generally considered non-sentient, the steam-powered lifeforms fill a variety of niches and may be partially responsible for the atmosphere in the bridge structure. These mechanisms are similar to the Flutter Butts and it is unknown if they are related.
There are other life forms that have fallen into Bridgespace, and it has become its own world unto itself.