At Christie's, crypto art surrealist FEWOCiOUS auctioned off his art collection for $2.1 million. NFTs are blockchain-based tokens that can be used to prove ownership of digital goods like photographs or video files, as well as real assets. Since selling a Bitcoin-themed artwork last fall, Christie's has established itself as one of the leading venues for top-tier NFT sales. Beeple's digital collage, which sold for a record $69 million in March, remains Christie's most valuable sale.