A warning has been issued to dog walkers after a toxic oil berg appeared on a beach.
They have been asked to protect their pets from congealed palm oil which has washed up on the shoreline.
A pet owner flagged up a mysterious object and raised the alarm after an oil berg floated onto Anglesey beach in Wales.
North Wales Live reported Ian Carmichael tweeted a picture of the bright orange object after spotting it on the beach.
He wrote: "No idea what this is washed up on Porth-y-post beach this morning.. but the dog ran straight to it and rubbed herself on it leaving her bright orange! Dog walkers beware!"
A debate followed among Twitter users over what the mystery object could be.
Some speculated whether it could be ambergris - a solid, waxy flammable substance produced in the digestive system of sperm whales.
But it was later confirmed that the object was solidified palm oil - which is dangerous to dogs.
Frankie Hobro, director of Anglesey Sea Zoo, said: "This is a palm oil berg and it is common for large numbers of them to be washed up on beaches in the same area at the same time as they are produced by a ship washing out its ballast tank.
"The resulting oil bergs get carried off to shore and wash up on beaches, so large numbers of these could appear anywhere along the North Wales coast over the next week or so."
Ms Hobro urged dog walkers to be alert as any contact with them can be extremely hazardous.
She said: "Palm oil is a useful cleaning agent, so it is used by large ships to clean out their fuel tanks at sea.
"Unbelievably, it is perfectly legal for ships to dump palm oil into the ocean when they swill out their holds anywhere in the world, as long as they are at least 12 miles offshore!
"And the result is oil bergs like this one washing up on beaches. The colour varies and so does the size and shape - they can weigh up to a quarter of a tonne!
"Due to their high bacterial loading and smell, dogs find them extremely interesting and are immediately attracted to them, which is what happened to the dog owner who posted this photograph."
Oil bergs can be carried for thousands of miles in the ocean currents when they have been dumped at sea, then they are washed up onto the shore, either in large chunks, or broken down into smaller pea-sized pieces, often over large areas of coastline, where they can wreak environmental havoc.
In summertime when sea temperatures are higher the oil slicks they produce have been blamed for the death of seabirds such as gannets and for dead fish washing up on beaches.
Experts have warned they pose a severe threat to both humans and animals, as well as marine life and if the public come across any on the beach they need to beware.
