A giant replica of the moon which is displayed all over the world has gone missing in the post.
The 7m (23ft) orb, covered in detailed imagery of the lunar surface, has been created by Bristol-based Luke Jerram and was en route to a festival in Austria.
Mr Jerram said the disappearance of the structure, titled Museum of the Moon, was "really annoying and upsetting."
Courier firm TNT said it was looking into the issue.
Mr Jerram said the artwork has been booked for a series of public events across Europe over the summer.
He said: "It has huge implications for all these people who are looking forward to seeing this artwork, and they won't be able to as it's in some warehouse somewhere. We haven't got a spare.
"I hope TNT pull their finger out and try and find it."
Images taken by a National Aeronautics and Space Administration (Nasa) satellite were used by the artist to create the installation.
Each centimetre of the internally-lit spherical structure represents 5km (three miles) of the moon's surface.
The floating artwork, which is illuminated and accompanied by music from different composers, was created in partnership with the University of Bristol and the UK Space Agency.
Mr Jerram has also recently finished work on a related replica of the Earth, showing how the planet looks from space.
The Earth sculpture was recently unveiled at the Bluedot music and science festival at Jodrell Bank in Cheshire.