Fossil Agate

Tiny shell fossils and creamy pink tones against a dark background give fossil agate its lovely variegated effect. Shells or coral heighten its ancient and natural beauty.

Rhyolite

Rhyolite is a mottled mossy green, beige and grey volcanic rock with the occasional hint of peach.  Rhyolite is formed from rapidly cooling magma, often resulting in glassy inclusions. This stone can be found in large deposits near Yellow Stone Park in Wyoming, USA.

Petrified Wood

Petrified wood (from the Greek root "petro" meaning "rock" or "stone", literally "wood turned into stone") is a type of fossil: it consists of fossil wood where all the organic materials have been replaced with minerals (most often a silicate, such as quartz), while retaining the original structure of the wood. The petrifaction process occurs underground, when wood becomes buried under sediment and is initially preserved due to a lack of oxygen. Mineral-rich water flowing through the sediment deposits minerals in the plant's cells and as the plant's lignin and cellulose decay away, a stone mould forms in its place.  In general, wood takes less than 100 years to petrify. The organic matter needs to become petrified before it decomposes completely.

Ammonites

Ammonites are perhaps the most widely known fossil, possessing the typically ribbed spiral-form shell as pictured above. These creatures lived in the seas between 240 - 65 million years ago, when they became extinct along with the dinosaurs.
The name ammonite originates from the Greek Ram-horned god called Ammon. Ammonites belong to a group of predators known as cephalopods, which includes their living relatives the octopus, squid, cuttlefish and nautilus.