When sets are put together, art swaps happen all the time: the art commissioned for one card does a better job of illustrating a different card, so the art gets moved around. This happened for a few of Mirrodin's Myr artifact creatures. Can you remember to which cards each of the pieces below were moved? (Click on the images along on the left below to see what card that piece was originally comissioned for.)
The art commissioned for Silver Myr was this:
The art commissioned for Iron Myr was this:
The art commissioned for Leaden Myr was this:
As it happened, Kev Walker created an entirely new set of art for the cycle of 1/1 mana-producing Myrs, which freed up those original Greg Staples pieces to move to other cards. Myraculous.