The large one (ø 48 mm) I found 3 years ago on the beaches of western New Foundland, it wasn't easy to find an intact one. The tiny ones (ø 3-9 mm) I found here in Scheveningen, some weeks ago. Apparently spring is also the time for marine reproduction, they look like babies don't they? I also noticed loads of baby "scheermessen" (razor shelles, Ensis arcuatus).
For a close up of the large one click 'Read more'
