Before he left, one evening, Mike pulled out of his pocket a black stone. It's about the size of a small oyster, and oval-shaped. It's perfectly smooth, and seems almost warm to the touch. I picked it up and looked at it, and realized that it has grain. It's actually a piece of petrified wood.
He couldn't recall where exactly he'd gotten it. Just picked it up and put it in his pocket because he liked it. He left it on the table.