W280xD220mm, China
A large Chinese river clam which belongs to the Lamellibranchia family. Some of species of the clams are able to produce pearls, there are stories of these clams being able to light up the lake (possibly at the time when there was no artificial light and a full moon, some of the light could possibly been reflected on the pearl in the shallow part of the lake). Whether these stories were true or not it certainly get my imagination going.
For the oversize aged creatures, trees, turtle, foxes, etc., there are myths of them becoming monsters and goblins. Here is the story about what goes on in the palace of the sea, with the appearance of the lobster, clam, cochlear, turtle goblins … Perhaps this slightly oversize shell contained a goblin to be over 100 year ago.
Mountain Folkcraft 