Primal Clay is a rare Artifact Creature — Shapeshifter card from Classic Sixth Edition (6ED), collector number 308. Current market price: $0.38, 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.)