You can find one randomly on a walk. It's rare though, so good luck.
I've been playing for a long time, and I think it's the meteorite.
This is how I know that you can get it. Maybe it can help you. When you are walking your dog if your lucky you can get meteorite or you can use action replay and use the cheat having every item. Hope it helps you!
No, the Briard is not available in all version of Nintendogs and Nintendogs and Cats.
No. Unfortunately Nintendo added no weather to the Nintendogs or Nintendogs + Cats games.
No. A meteorite is a rock.
No, because Pokemon is not in Nintendogs.
No, the Kelpie is not available in Nintendogs.
It is not possible to get a trampoline on Nintendogs.
Nintendogs happened in 2005.
No, the Afghan Hound is not available in all version of Nintendogs and Nintendogs and Cats.
Meteorite
A meteorite that originates from Mars.