The nautilus shell is one of the ocean's most beautiful creations. It is particularly aesthetically pleasing because its shape is governed by a logarithmic spiral, a type of spiral curve often seen in nature. The distances between the turnings increase by geometric progression. This pattern can be seen everywhere from shells to cloud structures to the shape of spiral galaxies. Here we have encased a logarithmic spiral in a 1" glass tile pendant. (Based on image by Chris73, design CC 3.0 licensed) The back of the pendant is sealed with a jewelry-grade resin and is water resistant (although just to be safe, still take it off before diving in the ocean). The bail is silver-plated and on your choice of a black leather cord with a silver clasp, or a silver chain. Both options are adjustable from 16" to 18".