These Trilobite fossils are sold in two parts: the positive and negative mold of the animal. They are found in nodules, irregular lumpy rocks which can be cracked open to reveal the fossil inside. Often dusted with rusty-colored limonite crystals, these
Flexicalymene trilobites exhibit lovely detail.
Trilobites are a type of extinct arthropod probably most closely related to modern Horseshoe crabs. With a growing number of predators and adapted to diverse habitats, various species of trilobites developed complex eyes, retractable antennae, and even protective spines. Trilobites ranged in size from head-of-a-pin tiny to more than two feet long. Their exoskeletons were composed of extremely hard calcite and calcium phosphate minerals to protect the soft internal organs, and as a result they are quite well represented in the fossil record.
We also sell these trilobites in a rougher,
less expensive variety.
Though Individual fossils vary in shape and color, yours will resemble the pictured example. 
