Translated from NOS TV in the Netherlands today:
Gemstones expert Hanco Zwaan of the Leiden museum has examined the oyster, which was found last month by a fishmonger from Yerseke, with X-rays. Under the mollusk’s body eleven more pearls turned out to be hidden. The find is very special, says Zwaan.
See also here.
This 16 December 2016 video is about the finding of the 21 pearls in Naturalis museum.
This 2014 video is called How Do Oysters Make Pearls?