The native or common oyster, Ostrea edulis, has been almost wiped out in UK waters by overfishing and by trawling the seabed.

Its survival was not helped in the 1960s, by the already depleted species being replaced in restaurants and in oyster farms by the less tasty but larger and faster-growing rock oyster from Japan.

This pushed a delicacy – so beloved by the Romans that they towed cages full of them back to Rome behind their ships – on to the red list of endangered species.

Now the Wild Oysters Project is trying to rescue the native species by recreating the oyster reefs that also used to provide excellent habitat for dozens of other sea creatures.

Scientists believe that by hanging cages full of adult breeding oysters near suitable seabed containing masses of old shells, which the oysters need to form new reefs, colonies will form naturally.

Among the oddities of oysters is that they are born male and change sex to female as they grow but individuals can also have both sex organs and fertilise themselves.

Each oyster can produce thousands of eggs so can multiply rapidly. This is good news because oysters clean our seas in search of food, each adult filtering up to 50 gallons of water a day.