I took a walk to the beach today and had it practically to myself in the rather cold wind. Undeterred I went down on the sand to get close to the sea and found these peculiar jellies, all along the waterline. They're in different sizes from about 3 to 9 cms across with lovely reddish centres. In the small ones I could see 4 quarter sections but the larger ones looked rather like those clear glass paperweights with patterns in the base. I picked one up and looked at the underside and it was almost as smooth as the top. I wished I had put my sketchbook in my pocket as I had to draw these from memory. Does anyone know what they are? I'm fascinated as I've never seen such creatures before!