More than 1,000 mysterious blue balls washed up on beaches in the UK this week.
Hundreds of rubber-type balls have been found on the Tees Valley shores over the past four days.
Experts at the Tees Valley Wildlife Trust said the balls came from Hartlepool Power Station, which uses the abrasive balls to clean the system's pipes.
Called ‘Taprogge balls' by their manufacturer, the balls are rarely released into the sea, but sometimes need to be jettisoned if there is a sudden build-up of pressure.
Locals say that recent storms have disturbed a large group of orbs on the seabed, throwing them back onto the shores.
Energy company EDF, which runs the power station, claims there has been no recent release, leading many to suspect strong winds and currents are to blame.
While the balls are biodegradable, they take two years to fully degrade, posing a threat to local wildlife.
Jacky Watson, Wilder Coast Officer at Tees Valley Wildlife Trust, said: “My aim with the project is to get people to do what they can to help stop pollution in the sea.
“The little blue balls are made of natural rubber, they are used to rub the pipes of Hartlepool Power Station in the cooling system.
“The cooling system uses sea water and they have to blow up the pipes to get the sea creatures out.
“They do that every week, they pass with the balls. It is a closed system and the balls must not escape. Every now and then an incident happens and they get away. If there is too much pressure, they break free and go into the river and sea.
“They are natural and biodegradable, but they are still a risk. They are supposed to biodegrade in two years, but that is still a long time.
“We have a very old nuclear power plant, it's about 40 years old. We still want to do something about it, along with many beach cleaning groups along the coast. They collect them.
“I contacted EDF and found that the environmental compliance officer is interested in speaking with us.”
Ms Watson and her team are asking the public for their help, using the locations of the ball discoveries to trace their movement on a map.
He added: “We were getting the word out locally if people found the balls they could let us know and EDF with what3words.
“What they didn't realize is how far south they go. There is a nice map now to see where the current is depositing the balls.
“I've had reports of over 1,000 balls just in these last few days. In the last few days the storm has disturbed somewhere a deposit of balls on the bottom of the sea.
“We think they were all raised together. They think they are historical. If balls are released it is very serious.
“There were some releases about a year ago and a detailed report was made.
“They are found in small numbers on a regular basis, mostly one or two. The community is involved, people are really getting into it.
“In the last few days it has gone nuclear. It's important to show that you can communicate with these big companies.”