Trilobite Fossil in Shale

Nicely defined fossil trilobites embedded in shale matrix.  Great tile pieces for a project or specimen piece.  2.5 inch x 1.5 inch approximately.  Shapes are irregular and exact size varies.  

Trilobites are ancient bottom dwellers having a three part/lobed body.  They are extinct anthropods, related to crustaceans.  They lived approximately 500 million years ago.