Copper Carapace is a common Artifact — Equipment card from Modern Masters 2015 (MM2), collector number 205. Current market price: $0.13 (foil $0.23), TCGplayer market prices via Scryfall.
Equipped creature gets +2/+2 and can't block. Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)