Asked by: Connor Dooley, Southampton
The sound has nothing to do with the sea, nor the shell’s oceanic origins. It’s simply the result of the effect of the shell’s shape on air trapped inside. Unable to escape, the air vibrates at frequencies dictated by the size of the shell, creating a mix that sounds a bit like waves on shingle. You can create a similar effect just cupping your hand over your ear.
Robert is a science writer and visiting professor of science at Aston University.