On the topic of unusual creatures, here's one of my more unorthodox creatures:
It's a living Poison Mine shotgun.
It operates by stockpiling Poison Mines within its "chamber", before spewing out all the mines at its target. The mines travel a surprisingly long distance, allowing this creature to attack at a range further than any species so far.
It has also covered itself with spikes as a deterrent, as it is rather fragile (a single structure connects the whole "chamber" to the core; deterrence is much needed!) for what it is.