bee yourself

My in-laws graciously bought us a barbeque, so we moved our old one and are planning to give it away. When I opened it to take pictures of the broken inside, I noticed bees. Upon closer inspection, we found them to have begun a nest inside.

I find myself wondering what their nests are made of, and what that silvery looking stuff is that the nest appears to be hanging from. DH tells me that these aren't the kind of bees that make honey; they are the kind that can sting you multiple times without consequence, so I will be glad to get rid of it. I put a warning on the ad, but I'm still a little concerned about giving it away.