PALO ALTO, Jan 20 (Reuters) - Twitter Inc(TWTR.N)on Thursday announced the launch of a tool through which users can showcase non-fungible tokens (NFTs)as their profile pictures, tapping into a digital collectibles craze that has exploded over the past year.

The feature, available on iOS to users of the company's Twitter Blue subscription service, connects their Twitter accounts to crypto wallets where the users store NFT holdings.

Twitter displays the NFT profile pictures as hexagons, differentiating them from the standard circles available to other users. Tapping on the pictures prompts details about the art and its ownership to appear.

Like other tech companies, Twitter is rushing to cash in on crypto trends like NFTs, a type of speculative asset authenticating digital items such as images, videos and land in virtual worlds.

The social media platform last year added functionality for users to send and receive Bitcoin.

Sales of NFTs reached some $25 billion in 2021, according to data from market tracker DappRadar, although there were signs of growth slowing toward the end of the year.

Proponents of "Web3" technologies like NFTs say they decentralize ownership online, creating a path for users to earn money from popular creations, rather than having those benefits accrue primarily to a handful of tech platforms.

Critics dismiss the decentralization claims, noting that many of the services powering adoption of those technologies - like the six crypto wallets supported by Twitter's NFT product - are backed by a small group of venture capitalists.

In a widely circulated tweet after the launch, security researcher Jane Manchun Wong highlighted one of those links, showing how an outage at venture-backed NFT marketplace OpenSea temporarily blocked NFTs from loading on Twitter.

OpenSea did not immediately respond to a request from Reuters for comment.