NFTs are generally represented by a form of token called the ERC-721. It’s just as simple to locate this token’s whereabouts as ether (Ethereum’s in-house currency) and other tokens such as ERC-20s. The NFT marketplace SuperRare, for instance, sends tokens directly to buyers’ wallets, where their movements can be tracked rather easily. The token can then generally be found under the ERC-721 tab.
OpenSea, however, has been experimenting with a new new token variant: the ERC-1155, a “multitoken” that designates collections of NFTs.
This token standard, novel as it is, isn’t yet compatible with Etherscan, said Williams. That means ERC-1155s saved on Ethereum don’t show up, even if we know they are on the blockchain because the payments record is there, and the “smart contracts” which process the sale are designed to fail instantly if the exchange can’t be made.