Why yes, that is a natural gas line running to the furnace and water heater: https://www.reddit.com/r/electricians/comments/1fpo26t/not_something_you_see_everyday_evidently_this/
Not something you see everyday. Evidently this image has gone a bit viral, but this is a friend of mines house. She hit me up wondering if I knew what might cause it. The flex was pulling about 175 amps and was at 1200 degrees. There's to be a whole news story on it and everything.
Mother of god, dare I say this post..... blew up. There are a lot of questions and there is no way I can get to everyone. Basically, during a storm a tree fell on the incoming lines and it caused some fucked up high voltage things and created a new ground.
Heat transfer is kind of like electricity transfer. It'll always travel the path of least resistance. It's the principle of the trick where you hold a lighter up to a super thin plastic water bottle or a balloon with water, the plastic won't melt until the water gets hot.