
Left: M31, Spiral Galaxy in Andromeda Right: Gastropod exoskeleton, Sanibel Island
Seashells are the exoskeletons of mollusks such as snails, clams, and oysters. They have three distinct layers and are composed mostly of calcium carbonate with only a small quantity of protein. These shells, unlike typical animal structures, are not made up of cells.
I picked up the shell shown above on Sanibel Island. It is the exoskeleton of a gastropod, more commonly known as a snail, and is part of a large taxonomic class within the phylum Mollusca. The class includes many thousands of species of sea snails, as well as freshwater snails, limpets, and land snails, second only to the insects in overall number. The fossil history of this class goes back about 500 million years. There are 611 families of gastropods known, of which 202 are extinct and appear only in the fossil record. They are the most highly diversified class of mollusk with 60,000 to 80,000 living species.
Often, I look up and marvel at the Milky Way, its 400 billion stars, and the galaxies beyond, the faint smudge of Andromeda. Today, I look down and marvel at the beauty of a very small part of the Milky Way: The delicate exoskeleton of a snail.
Calm is the soul that is emptied of all self,
In the eternal moment of co-inherence.
A happiness within you – but not yours.
Dag Hammarskjöld













