Massive lion's mane jellyfish washes up on Co Down beach
It is bigger than a dustbin lid - and it is coming to a beach near you.
This huge lion's mane jellyfish was found washed up on the beach at Greencastle in Co Down earlier this week.
Rebecca Hanna, who snapped the creature in a shot with her dog Coco, said swarms of them had been appearing along the Co Down coast.
"I'm down on the beach walking the dog three or four times a day and Coco my dog was standing beside this jellyfish," the Pets At Home manager added.
"She's a fully grown chocolate Labrador, and I got a picture to show my friends on Facebook the sheer size of the jellyfish.
"I've been seeing lots of them over the past week, but this one was longer than her - even if she was fully stretched out."
Rebecca told the Belfast Telegraph she had seen lots of normal moon jellyfish this summer.
In the last couple of weeks, she has seen at least 14 huge lion's mane jellyfish and photographed seven or eight - but this was the biggest one yet.
Needless to say, she has not been swimming at the beach since the invasion began.
"It's (hard) trying to keep the dog out of the water - it isn't easy," she said.
Rebecca Hunter, from the Northern Ireland Marine Task Force, said the organisation had been seeing unusual patterns this year, with virtually no sightings of lion's mane jellyfish around the south coast of England and Wales, but unusual trends in the Irish Sea.
"We've had reports of some really large ones along the east Northern Ireland coast, but nothing seems to have been reported from the north coast at all, which is unusual," she added.
"They can be very easily influenced by the weather. We seem to be having a lot less, but the ones we have are bigger.
"We're seeing unusual patterns around the whole of the UK and Ireland as well."
Lion's mane jellyfish get their name from the mass of long tentacles and their orangey brown colour.
The jellyfish only live for one year, and adults are usually seen around our waters in mid to late summer (June to September), although juveniles can be seen as early as February.
Their bell-shaped body, the umbrella, usually grows to around 30-50cm in diameter, but has been recorded much larger - some jellyfish over two feet in diameter have washed up around our coast.
They can be seen in large swarms, possibly due to storms pushing them together.
Lion's mane jellyfish have a very strong sting which can still hurt long after they have been washed up.