A Japanese magazine has revealed an alternately colored Magearna with a caption that reports it being the appearance it had 500 years ago. This does not conclusively mean it is the shiny coloration as well, but it seems likely. Magearna will be an event Pokémon for the upcoming games Pokémon Sun and Moon.
Also, we have images of the icons which will appear for the games on the 3DS menu. Cool!