Ecological implications and technological applications. (A) Speculative presence in extreme environments; (B) potential role in biogeochemical cycles and ecosystem functions: driving forces behind Earth’s matter cycling; (C) significance in dark, oligotrophic environments: new insights into microbial survival strategies; (D) coexistence with other energy harvesting strategies (mixed trophic systems); (E) bioelectronic devices powered by piezoelectrotrophic systems; (F) environmental sensing and monitoring applications; (G) bioremediation possibilities using mechanical energy in contaminated sites; (H) energy harvesting from ambient mechanical sources (vibrations, fluid flow, pressure).