The structure of the gastropod shell forms a logarithmic spiral first described by Descartes and later by Bernoulli. Good ol’ Jakob called it the “marvelous sprial” or the Spira mirabilis. Those who believe in crystals also believe the logarithmic spiral is part of the “sacred geometry”. Nothing displays this beautiful coiling in gastropods like x-rays of the shells. Pictures are from here and here. The second link contains several x-rays worth looking at.