Diatoms -- the most beautiful of the phytoplankton. Generally unicellular, they date back to the Jurassic period. In addition to being strikingly beautiful, the diatom showcased in this 1" glass tile also shares with many other diatoms a talent for sequestering phosphorus, making it potentially valuable in combating climate change (Image by Argonne, design CC 2.0 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 the pendant is hung on your choice of an 18" black cord, silver twist chain, or silver link chain.