Slugs

The slugs are an intelligent species of symbiotic invertebrates. They live among the nestbuilders, a post-intelligent arthropod-like species, and can be found living amongst the folds of nestbuilder exoskeletons. They can control their hosts directly through tendrils linked to the nestbuilders' nervous systems. They are blue.

Thanks to their symbiosis with the nestbuilders, which are not themselves intelligent and thus of little interest to the Inhibitors, the slugs were able to evade the Inhibitors for much of their history. Due to this they had enough time to research Inhibitor capabilities and design various weapons against them, although this ploy was mooted by the greenfly wave, against which their weapons were useless. These twin threats contributed to their opinion that vertebrate life, of which Irravel Veda (deployer of the greenflies initially) was and the Inhibitors had been prior to their assuming machine forms, was "all the same".