This appears to be a dead paper-wasps nest. I shuddered, got my gloves and used a wrench to knock it loose. The temperatures being below freezing, I wouldn't have expected any live wasps in the nest, but I was prepared to Run Away in case I was wrong. To my relief, the nest fell out to the ground and a swarm of angry stinging insects did not pour forth from it.
I have no idea how long that wasp nest was there. I could have been carrying it back and forth between Fernley and Fremont all summer long and not known it.