The co-founders of Gemini-owned non-fungible token (NFT) marketplace Nifty Gateway are stepping down and leaving the crypto exchange to eventually start another company.

Duncan Cock Foster, who founded Nifty Gateway with his twin brother Griffin Cock Foster in 2019, tweeted Wednesday about the departure.

lSome news n after almost 4 years, @gcockfoster and I are departing @gemini and are passing the baton at @niftygateway,r he wrote. lThis journey has been an incredible ride, but Griffin and I are founders at heart and we want to start another company.r

Duncan Cock Foster said he and his brother would be replaced by vice president of engineering Eddie Ma as technical leader, and director of collector services and growth Tara Harris as non-tech leader. He added that he and Griffin would continue with the company as advisers to ensure continuity.

Gemini acquired Nifty Gateway in late 2019, with Duncan and Griffin teaming with another set of twins at Gemini n co-founders Cameron and Tyler Winklevoss n to provide the back-end infrastructure to allow traders to purchase NFTs with fiat.

NFT trading volumes have fallen 94% in the past year, however, and Gemini has faced a series of challenges, notably having to halt withdrawals by its Earn customers because of problems at its partner on the product, Genesis Global Capital. Genesis filed for Chapter 11 bankruptcy last week, with documents showing that it owes $766 million to Gemini. (The parent company of Genesis is Digital Currency Group, which also owns CoinDesk).

On Monday, Gemini laid off 10% more of its staff, following two rounds of layoffs that began last summer.

Duncan Cock-Foster said in his tweet thread that he and his brotherrs immediate plans are to take a break.

"Our first step will be to take a sabbatical, digest what has happened over the five years since we started Nifty Gateway, and start brainstorming new startup ideas,r he wrote.

Duncan Cock-Foster declined to comment further on the nature of his departure.