In the Victorian era they were sold for a king's ransom. These are the rare black freshwater pearls that poachers used to keep a keen eye out for along stretches of the Rivers Ehen and Irt in West Cumbria.
Now in the 21st century parts of the River Ehen valley are being turned into a Site of Special Scientific Interest (SSSI).
The new SSSI status is to help protect the unique freshwater mussel, which in the past produced a freshwater pearl for the Queen. The freshwater mussels on the River Ehen are said to be the only ones breeding at the moment in Britain and each mussel can live to be 120 years old.
It is illegal to kill or damage the freshwater mussels. The even rarer black pearls that grew in mussels on the River Irt are thought to have led to the mussels vanishing from the River Irt.
Dr Parkers history of the Gosforth District states: "The locally famous pearls of the Irt appear to have been known to the Romans. Tacitus and Bede mention British pearls andCamden saysof the Irt "In this brook the shell fish eagerky sucking in the dew, conceive and bring forth pearls, or to use the poets words 'shell berries'. These the inhabitants gather up at low water and jewels buy them." About 1695 a company was formed to search for pearls in the Irt and Thomas Patrickson of HowHall Ennerdale is said to have employed people to gather £800 worth The pearls are still to be found by careful searchers.''
Because the mussel's eggs are at one stage carried inside trout and salmon the SSSI change could help protect the trout and salmons' environment. But SSSI status could also bring extra requirements on farmers and landowners.
Explaining the planned SSSI, Alan Stewart, Conservation Officer for English Nature said: "We will be seeking to designate three rivers in Cumbria, The Derwent\Cocker, the Ehen and the Eden. We are at the stage of contacting landowers, local councils and the angling associations.
"There has been a survey done this year of the mussels and the bulk are between Ennerdale Lake and the confluence of the River Keekle, so that is the area we seek to make an SSSI.''
He conceded that the Keekle carried the treated outflow from Cleator sewage works into the River Ehen.
Mr Stewart added: "the new designation could help bring pressure to bear on North West Water.''
A spokesman for North West Water said : "We have had no failures this year to meet the standards laid down at Cleator. We comply with the standards set down by the Environment Agency. Our discharges are fully treated.''
Mr Stewart said the main effects of the SSSI would be threefold; Any planned development would have to be referred to English nature for consultation, landowners would have to notify any works that may affect the riverbanks and grants could be made available for works that benefit the natural habitats on the river.
English Nature have their area offices at Blackwell, Bowness on Windermere, LA23 3JR.
A member of the Egremont Anglers Association said: "The Ehen could even become a special European Sensitive Waters area.'' He said the level of fish stocks on the River Ehen "were poor and any such conservation protection such as the SSSI was to be welcomed''.

In 2003 the Environment Agency stated they planned to assist the musels to reproduce by moving examples from site to site...Whether thos also spreads viruses or infections one wonders..The Agency stated :Enjoying one's own space may suit some, but for pearl mussels it is having a devastating effect. For this rare species, living together is essential to successful reproduction, as sperm released into the water by males is filtered by the gaggles of females that share their living space.

However, due to a number of reasons, pearl mussel populations in English rivers have become fragmented. Many now live near-solitary lives on empty beds, their sex life a long-distant memory. As a result, while the species continues to thrive in Scotland and Ireland, the numbers of English and Welsh pearl mussels is dwindling alarmingly. To find out more check out their information.

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