One of the big rumors surrounding Batman V Superman: Dawn of Justice is that Lex Luthor gets his hands on the remains of the World Engine from Man of Steel and uses it to synthesize Kryptonite. That would make the major weakness of Superman a big piece of the story in the movie, when they made the choice to exclude it from the first film.
Now the Prop Shop has received a prop newspaper from Batman V Superman: Dawn of Justice, and one of the images is of someone holding a green rock. The text on the paper is readable, but it doesn’t talk about the mysterious image of a rock that could be Kryptonite.
In respecting the site’s wishes of not others reposting the image, you can check out the newspaper at the Prop Shop’s website here.