I have a main drain line running from my 1940s era single family residence in Las Vegas, NV to the city sewer. Given the time period I had assumed it would be cast iron, but when I dug down to it, it didn't quite look like cast iron I'd seen before. It has a distinct hammered, shiny finish and has zero corrosion, despite being buried in the ground for (I assume) nearly 80 years. Can anyone verify that cast iron looks like this sometimes? If not, what else could it be?
Thanks in advance!

