The discovery of filamentous Desulfobulbaceae in 2012 elucidates the cause of the small electrical currents in the top layer of sediment on large portions of the ocean floor. The currents were first measured in 2010. Thousands of these currently unnamed Desulfobulbus cells are arranged in fibrous microorganisms up to a centimeter in length. They transport electrons from the sediment that is rich in hydrogen sulfide up to the oxygen-rich sediment that is in contact with the water. 
^Larsen S, Nielsen LP, Schramm A (September 2014). "Cable Bacteria Associated with Long Distance Electron Transport in New England Salt Marsh Sediment". Environ Microbiol Rep. doi:10.1111/1758-2229.12216. PMID25224178.