Unearthed from the fuel tank, this piece looks like it has been salvaged from the sea floor. It is (or was) the business end of the fuel sending unit. The metal rod, partially in view, is connected to a plastic float at the extreme end. This float will bob up or down and mechanically position the arm as the fuel level changes. That pivot point, behind the gruesome mess, is locked up solid. I will attempt to chip away the corrosion and free the shaft.  Peering into the tank itself revealed no similar horrors.  Plenty of debris and rust but no stalactites or stalagmites artefacts.  It will need to be boiled out.