An artist sneaked an AI-generated print on to a gallery wall before bemused visitors alerted museum staff.
The print was hung up at National Museum Cardiff by secretive artist Elias Marrow, who said his Empty Plate piece - depicting a young boy in school uniform holding a plate - was viewed by a "few hundred people" before it was removed.
One visitor who noticed the artwork asked a member of staff about it, but said the museum worker "admitted they had no idea about the piece or when it arrived".
An Amgueddfa Cymru spokesperson said: "An item was placed without permission on a gallery wall in National Museum Cardiff. We were alerted to this and have removed the item in question."
The artwork, generated using artificial intelligence before being printed off, was hung by Marrow in the museum's Contemporary section, with his website saying Empty Plate "represents Wales in 2025".
