The Richard Nixon administration in the United States gave away 270 pieces of moon rock to countries around the world. A staggering 180 of them have gone missing, and one of the two which Malta owns has been stolen.
The National Museum of Natural History in Mdina housed one of the two Maltese moon rocks, but it was stolen in a raid in May 2004. It’s still not known where it is and an amnesty was held to try and recover it, as the item itself is impossible to sell on the open market. It’s an unfortunate loss, and it was also the most valuable item in the museum’s collection.
The other piece of moon rock in Malta is still safe and is located at the Gozo Museum of Natural Science.