Huge prehistoric oyster could contain world's biggest pearl

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A giant fossilised oyster donated to the Blue Reef Aquarium in Portsmouth is to have an MRI scan, to see if it contains an enormous pearl.

At 17.5cm/7" wide and 7.5cm/3" thick, the shell is ten times larger than a normal oyster and is thought to be between 65 and 140 million years old. If it does indeed contain a pearl, it could be as large as a golfball — the average size of a pearl is 7mm!

The fossilised oyster was caught up in the nets of a trawler boat in the Solent.

Blue Reef's Lindsay Holloway said: "Initially they thought it was a real oyster but realised it was actually a fossilised one when they got a closer look at it.

"Oysters can be aged by annual growth rings on their shells and we have counted more than 200 rings on this oyster making it an extremely long-lived individual." Modern oysters typically live an average of six years.

The aquarium is hoping to arrange for the fossilised mollusc to undergo an MRI scan to check whether it contains a pearl.

There are dozens of different types of oyster alive today and virtually all are capable of producing pearls. However only pearls from certain species are deemed to be valuable.

UK oysters are commonly thought to be among the world’s finest. They take five years to mature and are protected by an Act of Parliament during their May-August spawning season.

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