In both of the official artworks we got for the Delta Episode, the battle between Rayquaza and Deoxys causes an explosion of small meteorites to rain down onto the planet.

The fact that the artist chose to include this in both works could mean that the rocks are significant, and I'm guessing that they're mega stones to be grabbed in the post-game. Similar to XY, doing the Delta Episode "unlocks" the new stones. This would be much more believable than that "UPGRADE YOUR MEGA BANGLE WITH THE SUN DIAL" bullshit.

What do you think?