Writing (About) Life--Meteor? "Meteor-ish? or...What Is It?

My son texted me this morning, asking if I'd find the odd rock he'd found in a creek near the house when he was a boy, take pictures of it and send them to him. Oh, sure. Why not? So I found the rock. I took the pictures. I sent them to him. And I thought I'd show them to you, while I was at it. All I know about it is that he found it in the creek, it has several flattened "facets" on the surface, it's not magnetic, and it's noticeably heavy for its size.
What do you think it is?