Eel-men
Some organics' bodies deteriorate too quickly to regrow. They may replace perished sections with mechanical substitutes.
A sub-human might have their bodies replaced out of necessity to survive, or out of lust. Radiation from the ambient space screws with organics' bodies, and will gradually drain
their bones away. They can insert metal stints to keep their backs straight, but after the softer flesh slips off, a metal injector is needed.
Organics in their search for ignorance might enthusiastically replace their bodies. They will forgoe a lot of sensation for easier mind control.