Arcbound Worker is a common Artifact Creature — Construct card from Darksteel (DST), collector number 104. Current market price: $0.34 (foil $3.52), TCGplayer market prices via Scryfall.
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)