Presumably created by an older civilisation, these constructs appear to be a primitive version of the more modernised Iron Golems.

Despite being an older variant of a more modern technology, they are equally as capable as their newer counterparts, and in some ways still even surpass them.
Their alloy is significantly more resilient than an Iron Golem's, and their actuated appendages enhance their already hefty attack strength.
Contrastly however; their movement speed is quite a bit slower and almost entirely negates their threat.

It's believed they were originally used as workhorses more than combat drones, which would explain their enhanced strength and durability.
