Why do shells always spiral the same way?

On a recent trip to The Gambia the missus and I collected shells from the beach. We got plenty of spiral shells (as opposed to bivalves) of maybe 10 or 12 different types and every one of them had the spiral going the same way. Can anybody explain this or should I have just concentrated on my tan??!!

Why do shells always spiral the same way?
brainy question.



we know there's shells that go one way and there's shells which go the opposite way.



different species obviously have their predilection.

BUT I SUSPECT ITS LIKE 85% OF PEOPLE BEING RIGHT HANDED.....same as in shells. thats why you will find some shells of the same same species go opposite.



Laterality....this is more primitive than we acknowledge, sure we evolved to write with our hands, the snail evolved to make its shell....right handed ...more often than left, just like people
Reply:They don't all spiral the same way but most snail shells do go right handed not sure why though, sorry
Reply:If you travel to the other side of the world you'll notice that all the shells spiral in the opposite direction.
Reply:They don't. What you found was a sample of the way in which the majority spiral. However, there are some species that spiral the other way i.e. sinistrally.
Reply:It is uncommon but not rare for spiral shells to "go another way".

I have a "left handed" whelk (conch) shell I found on the beach in VA.

I have no idea why that is - maybe genetics???