It has since been determined with relative certainty that SPIDERs are mobile power sources for different AI communities. After humanity’s exodus underground due to atmospheric instability, a largely immaterial AI community took over Earth’s surface. However, still in need of an easy and reliable method of powering itself, the AIs created SPIDERs to use as mobile rechargeable power units.
It has been inferred that SPIDERs are almost completely self-sufficient machines because of their on-board, miniaturized hydrogen power plants. The ability to break down the molecular structure of water in order to utilize the hydrogen to power itself allows the SPIDER to be almost indefinitely maintenance-free. Furthermore, nanotechnology throughout the SPIDER maintains and repairs its hull and internal workings.
AI communities, as can be inferred, are based most densely around large fresh water deposits in order to maintain large hydrogen power plants. SPIDERs fill in the gaps in electricity in drier areas and provide emergency power when required. Despite their unique design and impressive stature, it appears that SPIDERs are low ranking in the AI community. Still, their purpose is important as the AIs continue to develop on the newly vacated surface of Earth.