A strange oceanic scene at a beach in the north of England has perplexed both tourists and locals.
At Saltburn-by-the-Sea in North Yorkshire, thousands of dead and dying mussels washed up on the strand on Tuesday.
Dead mussels, starfish, crabs, and razor clams welcomed people strolling along the seafront.
The area previously saw a mass crustacean die-off in late 2021 and major concerns were raised about dredging in the River Tees.
The Environment Agency said high tides and stormy weather would ‘most likely be the cause’ this time around.
Stuart Marshall owns beach huts on the promenade and organised a clean-up of the area.
He said: ‘It’s devastating. There’s starfish dead, clams, oysters and crabs.’
A deposit of black debris arrived on the beach with the tide and some claim it is sea coal.
But Stuart does not think it is and added: ‘We do get bits of coal from time to time but not anything like this.’
He questioned if rough seas had killed the creatures and said the waters were calm lately.
Helen Whitworth, from Northallerton in North Yorkshire, was walking her border collie Drako on the beach.
She said: ‘This black area is not usually here. Usually it’s a really beautiful beach. There’s all sorts of debris here.
‘I’ve come down for a lovely walk with the dog and it’s such a shame to see all of this today.’
The Environment Agency confirmed it had not received reports of the washed up marine life.
A spokesperson added it is ‘normal at this time of year’ and high tides and recent stormy weather would ‘most likely be the cause’.
The previous mass die-off sparked a series of investigations which proved controversial.
A panel from the Department for Environment Food and Rural Affairs concluded: ‘A novel pathogen is considered the most likely cause of mortality.’
But it was ‘unable to identify a clear and convincing single cause for the unusual crustacean mortality’.
Some campaigners fear dredging for a new freeport on the Tees was linked to the die-off.
However, those claims were strongly disputed by Tees Valley Mayor Ben Houchen.