Hundreds of volunteers descended on the beaches of the North Sea coast this weekend to collect sea shells as a measure of the sea’s biological diversity. While there is a serious scientific purpose to the exercise, it is also a fun day out on the coast for Belgian, French and Dutch families with kids. On Saturday, Natascha Perales and her children marked a wide spiral pattern on the sand in Middelkerke, in Flanders, and filled their plastic buckets with shells. The harvests were taken to a sorting center run by volunteers, to be counted and divided up by species. “We found mussels, oysters, cockles, at least six different species,” 40-year-old Perales told AFP. “It’s a great activity, despite the weather.” Braving stiff gusts of wind, the dozen participants kept the Middelkerke collection point busy. Laurence Virolee, 41, came with her three children. “We learned a lot of things,” she said. …