This video says about itself:
Pacific Oyster Larvae (various ages)
22 March 2015
Snippets of Pacific oyster (Crassostrea gigas) larvae at different ages, 3d, 10d, and 18d post-fertilization.
Giant oyster in Belgium – 02-09-15
It was almost as long as the forearm of the finders, an oyster shell of 38 cm. This very large oyster was found on the beach of Knokke-Heist by a family from Luxembourg. The Flanders Marine Institute reported that it is a Pacific oyster. These oysters are known that they can be very large. Because probably this shell is the biggest one found ever the oyster has been reported to the Guinness World Records book.
Pacific oysters have not been for a long time at the Dutch and Belgian coasts. From the 1960s on, the oysters from Japan were bred in large numbers brought to Zealand. The Dutch oysters had been badly affected by a disease and oyster growers thought the Japanese oyster would be stronger. Growers expected that the Pacific oysters would not reproduce by themselves in the Dutch cold water and that they could bring the Japanese oysters safely to the Netherlands. Unfortunately, the cold proved to be no problem, since the mid-seventies they multiplied massively.