Primal Clay is a rare Artifact Creature — Shapeshifter card from Revised Edition (3ED), collector number 271. Current market price: $0.64, 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.)