Seashells

‘She sells seashells on the sea-shore' - do you remember that tongue-twister? Apparently, it was originally a song written in 1908, inspired by Mary Anning’s life – she was a Victorian fossil hunter from Lyme Regis in Dorset, England, whose father often took her and her brother on fossil-hunting expeditions to supplement the family's income, and they offered their discoveries for sale to tourists on a table outside their home.

So, what do we know about seashells? How are seashells formed? Seashells come in an astounding variety - some are round, others long, some are smooth, others bumpy. Some are large, others small, and they come in a rainbow of colours, with these different colours possibly being to do with their diet. All that variety comes from the same source - little animals called molluscs, with a mighty muscular foot to help them move around.

No skeletons inside

Unlike humans and other animals with backbones, molluscs don’t have skeletons and are known as invertebrates. Many move through life with just their soft bodies, and some grow shells for protection, as a kind of travelling armour. The shell is a protective outer coating produced by the animal’s mantle, a layer of tissue that lies between the shell and the body.

There are many kinds of molluscs, both in the sea and on land, with and without shells. Snails and slugs in the garden are land versions.

A few days after young sea molluscs are born, they start building their shell, layer after layer. They use salt and elements from the sea (such as calcium and carbonate) and proteins from their own bodies to help them build their shells. Land molluscs obtain calcium from their environment in a variety of ways - they eat live and decaying leaves and wood, fungi and algae on wood and rocks, sap, animal droppings and carcasses, worms - and other snails.

There isn't an exact timeline for how long it takes a seashell to form, because the seashell is always being repaired and added to throughout the life of its owner, unlike the Hermit Crab, a crustacean, who discards its shell when it becomes too small and has to take over someone else’s discarded bigger one.

Where to find them

Seashells are commonly found on beaches, where natural debris gets deposited by the waves and the tides. Shells are very often washed up onto beaches empty and clean, their owners having already died, and sometimes they are found in unlikely places - shell deposits on mountaintops indicate that mountains were formed by the uplift of sea bottoms, and are not directly the result of - or evidence of - a global flood.

Our world is still an active place, with mountains being thrown up by geological forces, and then eroded to their roots, and if the land being thrown up started below the sea, then seashells will be found high in the mountains. Even atop Mount Everest - Called the ‘Qomolangma Limestone’ by geologists, the summit rocks are well-bedded limestone containing fragments of common marine shells. The summit was actually the seafloor around 470 million years ago, brought to the roof of the world through continual uplift caused by the collision of tectonic plates, the solid crust and the upper mantle of Earth. These plates can be compared to pieces of a cracked shell that rest on the hot, molten rock of Earth and fit snugly against one another.

Look but don’t take

There are plenty of beaches in Portugal where shells can be found, and I admit I have collected a few in the past. But now it’s illegal to take them home - authorities are cracking down, and if you're a tourist found caught with corals or seashells in your luggage, you now might face a fine or even imprisonment in some countries. Depending on the shell, you could be robbing an animal of a home, or building material, or even disturbing an entire ocean ecosystem. This could have dire effects on coastal populations, especially in combination with global warming and rising sea levels

They say seashells are like smiles from the sea, so be kind, and leave them be!

Marilyn writes regularly for The Portugal News, and has lived in the Algarve for some years. A dog-lover, she has lived in Ireland, UK, Bermuda and the Isle of Man. 

Marilyn Sheridan