This may mean we could use they oysters from tolo harbour for the cleaning part of the raft
“Tai Po was the centre of the local pearl industry. As far as we know, pearls were first collected from the nearby sea in AD 761 during the fourth year of the reign of the Tang emperor, Hoi Yuen. He established a monopoly on the pearl industry and, in AD 964, 8,000 soldiers were sent to Tai Po to protect it. The pearls and tortoise shells collected were highly prized and used to adorn an imperial palace in Canton, later burnt to the ground.