Primal Clay is a uncommon Artifact Creature — Shapeshifter card from Magic 2013 (M13), collector number 210. Current market price: $0.19 (foil $0.10), TCGplayer market prices via Scryfall.
As this creature enters, it becomes your choice of a 3/3 artifact creature, a 2/2 artifact creature with flying, or a 1/6 Wall artifact creature with defender in addition to its other types. (A creature with defender can't attack.)