‘D’ is for ‘Drones.’
The Drone-class of automaton is the most common in the world. Once upon a time they were cleaning and maintenance drones, sometimes used for defense or transportation, easier to manufacture, store and replace than slave labor. They are land-based and spherical, running on a sort of combustion engine that can utilize various compounds. For reasons no one has yet identified, they actively seek to combust biological compounds. They started with their creators, the gremlins, and have never let up. They are often found in packs, flocking around larger automatons, such as the Mammoths, former construction vehicles that have turned carnivorous.
I originally derived the name from ants, never anticipating the U.S. drone program to get so prolific and ugly. I’ve gone back and forth over this name. It’s perfect in-world, and honestly, the U.S. drone program is so heinous that the thought of the name now being applied to an unmanned killing machine that wiped out its originating society is artistically appealing. I’m inclined to keep it, but I’d love opinions on the topic.