According to experts at Tees Valley Wildlife Trust, the balls originate from Hartlepool power station, which use the abrasive spheres to clean the system’s pipes.
Dubbed ‘Taprogge balls’ after their manufacturer, the balls are rarely released into the sea, but sometimes need to be dumped if there is a sudden build-up of pressure.
Locals say recent storms may have disrupted a large gathering of the balls on the sea bed, launching them back onto the shores.
EDF, which operates the power station, claim there hasn’t been a release recently, leading many to suspect strong winds and currents are to blame.
Wilder Coast officer Jacky Watson from Tees Valley Wildlife Trust said: ‘My aim of the project is to get people to do what they can do to help stop pollution in the sea.
‘The little blue balls are made of natural rubber, they’re used to scrub the pipes of the Hartlepool power station in the cooling system.