EtherRocks is a collection of digital pet rocks that was released in 2017. In August, a single EtherRock sold for $135,240, with secondary market prices ranging from $96,100 to $1.9 billion. On December 25, 2017, the project's smart contracts were implemented, and the first EtherRock appears to have been auctioned on December 26. Only 100 NFTs will be produced, with the last one being sold in 2021.