A machine built to last and thrash, often created for the sole purpose of guarding something
A machine that is built to stay in one place and fire projectiles at enemies. Excellent for guarding a place that people aren't allowed to be.
Appearing as a 10-foot-long cockroach with tentacles instead of antennae, the iron eater is a creature that derives most of its sustenance from metal objects.
Much like its cousin in the same taxonomic family, the rust monster, the iron eater will voraciously eat any iron-based equipment that it can get its hands on, though unlike its cousin, it will also eat some wood, fabric, and precious metals in order to get a more balanced set of nutrients.