Agate is a striped chalcedony quartz that forms in layers and in a wide variety of colors and textures. An individual agate forms by filling a cavity in a "host" rock. As a result, agate often is found as a round nodule, with concentric bands. In ancient times it was said to quench thirst and guard against fever, and agate bowls were very popular in historical Europe.

Shells are mineral structures formed by aquatic creatures and land mollusks. Lustrous shells including mother-of-pearl have been carved into cameos and buttons since antiquity. The beauty and variety of shells make them a sought-after decorative material.