A few weeks ago I picked up this shell on Portobello Beach; the initial attraction was the collection of barnacles on the inside surface together with the failed kelp holdfast.
The barnacles will never grow up into geese as they have now been out of the water for far too long while the kelp should have chosen a more robust anchor. I remember, that many years ago, David Bellamy gave a talk on the origins of Chesil Bank in Dorset, it was formed by kelp being blown up onto the bank by storms and carrying the pebbles they used for anchors with them. These days I have no time for Bellamy and his misguided opinions on general science such as global warming, but he does seem to be pretty solid when he sticks to his own subject of botany (seaweeds are algae and are therefore included in the plant kingdom, I hope). He called the talk “Kelp Boats Is A-Comin’,” a parody on the 1951 song “Shrimp Boats.”