A monster barrel jellyfish has been spotted for the first time floating along - a British river.
The giant creature measuring around 4ft from head to tentacle was seen drifting along Cornwall's Helford River.
Several of the massive creatures have been found washed up on UK beaches in recent weeks but the latest invader was seen half a mile inland.
Barrel jellyfish are usually found in more tropical areas such as the Mediterranean sea.
The dustbin lid-shaped species is harmless to humans but with the weather warming up experts say more could be heading our way.
Wildlife cruise operators have already reported hundreds of the creatures off the coast of Devon, Dorset and Cornwall.
But rambler David Smith, 45, was visiting Porth Saxon beach, near Falmouth, when he watched the jellyfish turn into the Helford estuary before heading upstream.
He said: "It looked at first like a giant blancmange sitting on the water. I took a closer look and realised it was one of those rare jellyfishes that are making the news.
"I followed it about half a mile up the river before it eventually disappeared beneath the water. The thing moved at a snail's pace so I was able to get a few photos before it vanished."
Richard Harrington of the Marine Conservation Society said: "Half a mile up an estuary is not too far as they are relatively strong swimmers, but it was more likely carried in then out again by the tide.
"This type of jellyfish is a regular visitor to the UK, although we've had reports of some very big ones this year.
"This is the only species of jellyfish that can live for more than one season, so these larger jellyfish are probably adults who have survived through the mild winter."
Beachgoers are advised not to touch jellyfish in case they have chanced upon a species with a powerful sting.
The Red Cross says that anyone who does get stung should not try and use urine to provide relief as the healing properties of pee are an urban myth.
Vinegar is said to be far more effective.