Tens of thousands of dead herring have carpeted a stretch of coast in northern Norway - and then disappeared again.
The fish appeared on New Year's Eve, leading to speculation that predators might have driven a huge school ashore or the fish could have been washed on to the beach by a powerful storm that hit Norway on Christmas Day.
Jens Christian Holst of Norway's Institute of Marine Research said a combination of several factors was the likely explanation.
Local officials had also started to consider how to clean up the estimated 20 tons of dead fish on the beach in Kvaenes, north of the Arctic Circle, before it decayed. But before they could start, the fish disappeared.
Holst said the herrings have probably been washed back into the North Sea.