Beachgoers have been warned to watch out for killer Portuguese men o' war after a number of the creatures washed up on Britain's coast.
The jellyfish-like animal has venomous tentacles as long as 30 metres (100ft) that deliver a painful and sometimes fatal sting.
There have been an unprecedented number of sightings along Cornwall's Atlantic coast as it is pounded by high winds and waves.
See also: Invasion of giant jellyfish in Devon
Part of one beach was closed and warnings were issued for beachgoers after men o' war - also known as the 'floating terror', were found near Newquay and Bude, Cornwall Live reports.
Lifeguards confirmed that a section of Perranporth Beach was closed off on Tuesday morning after the creatures washed up.
Swimmers and surgers were allowed back in the water after the animals were removed.
Despite popular misconception, the man o' war is not a jellyfish but a Siphonophore, a colonial organism made up of specialized individual animals which work together in a balloon-like float.
They have been washed up alongside rare violet sea snails, which feed on the men o' war.
A group called Newquay Beachcombing made the discovery.
A spokesman said: "It's a great privilege to see these rare and beautiful creatures.The creatures have long tentacles which deliver a painful sting
"We had been finding the violet sea snails washed up on the north coast of Cornwall so were wondering if we would also start to find the Portuguese man o' war they feed on.
"Violet sea snails get their colour from Portuguese men o' war."
Cornwall Wildlife Trust, a marine conservation group, has had an unprecedented 144 sightings reported in the last three days.
The organisation said: "In previous years there have been a maximum of 40 reported in one year - 2000, 2009 - and only three reported in 2016.
"With strong westerly winds pounding our coastline we are getting many reports of Portuguese man o' war washing up."
Matt Slater, marine awareness officer for Cornwall Wildlife Trust, said: "This is an unprecedented event and we urge the public to be cautious and to keep an eye out for unusual species being stranded.
"We may see other rare warm water species washing up.
"Although the UK media always focuses on the dangers posed by their stinging cells to us humans, stings are incredibly rare and the man o' war is actually a beautiful lifeform, wonderfully adapted to life in the open ocean and are only seen in extremely rare cases on our shores."
Sightings can be reported to the Trust's Marine Strandings Network on 0345 2012626.
Marine groups are also investigating another reported sighting at Newgate in Pembrokeshire last Thursday.
Artist Mara Swift said the creature's body was about 15cm (six inches) long with the tentacles stretching three or four metres (10ft).
It is said that men o' war travel in groups of up to 1,000, using their stinging tentacles to capture food.
People should never touch or pick up the creature, as it may still sting them even weeks after washing ashore.
In July, dozens of jellyfish washed up on beaches in Cornwall.