Looks like a couple of Concretions fused together. Fairly common find actually. Still a very cool find. I bring them home all the time and put them around the fish pond.
Check out the ones in this link. You'll see they can make some amazing formations and all are 100% natural.
What in the world is that thing? I have several ideas, none are constructive so I'll keep quiet. Is that metal or maybe a hot rock? That is a very curious find, I love it!