The original tweet and a house on Mars (which is neither a house nor on Mars) are two of the latest bizarre non-fungible token (NFT) sales.

NFTs are having a moment. Grimes and Beeple are just two artists who have sold digital artworks using NFTs to confirm ownership in the past few months. Today, over $100m in NFT-recorded trades are reportedly taking place every week. Several companies have moved to capitalise on the trend. NFT marketplace OpenSea netted $23m in a funding round just last week.

Twitter CEO and co-founder Jack Dorsey has made no secret of his support for blockchain-based products, having previously offered cryptocurrency services via his other company Square.

Dorsey has now cashed in on the NFT mania by auctioning off the first tweet ever tweeted on Twitter for $2.9m. The tweet was posted on March 21, 2006, and simply says, “just setting up my twttr”.

The Malaysia-based buyer Sina Estavi, CEO of blockchain company Bridge Oracle, paid for the tweet using the Ethereum cryptocurrency.

“This is not just a tweet,” he tweeted. “I think years later people will realise the true value of this tweet, like the Mona Lisa painting.”

Dorsey now plans to donate the proceeds of the deal to the Give Directly’s Africa Response fund, the BBC reported.

Elsewhere, artist Krista Kim has sold a virtual home named Mars House for 288 ether ($512,000) on NFT marketplace SuperRare.

“Mars House is the first NFT digital house in the world,” SuperRare said. It is actually a set of 3D files and a “calming musical accompaniment” which the buyer can upload into an Augmented Reality (AR) platform. Kim continues to own the copyright to these files, and the buyer undertakes to delete them in the event of selling the “House” to someone else, at which point Kim will update the NFT blockchain to confirm change of “ownership” and supply copies of the files to the new buyer.

In what sounds like the most expensive version of the Sims ever sold, having put the files into an AR system the buyer can take virtual tours of the house, which was designed to make it a place for meditation and tranquillity. It was rendered using the Unreal Engine, which also powers games like Tekken 7, Final Fantasy VII Remake and Fortnite.

The artist also envisions that the house might be used in AR-powered apps like SuperWorld, though the buyer would need to also buy some pretend land to put it on.

“Soon, we will all live in AR through our real environments using SuperWorld, a new app that has mapped the entire world for AR interface,” Kim told Dezeen.

“Virtual real estate based on the real world can be purchased on SuperWorld, and in the very near future, this app will allow us to mint 3D NFTs and create a marketplace of digital AR assets.”

NFTs are not new, having been around since at least 2012. While they gained some attention during the CryptoKitties craze of 2019, they have more recently been in the public eye thanks to eye-wateringly big deals.

People championing the trend have argued that NFTs’ ability to prove ownership and authenticity can provide artists and businesses with opportunities to create new revenue streams.

For instance, Dorsey’s interest in cryptocurrencies and his latest foray into NFT auctions have amplified rumours that Square’s recent acquisition of music-streaming platform TIDAL could mean that the businesses plan to introduce NFTs soon.

Read more: It’s pretty, but is it Art? NFTs can’t tell you, but they do prove who owns it