Rare Unique Pyritized Brachiopod. These pyritized brachiopods (Paraspirifer bownockeri) are from the famous Sylvania Quarry in Ohio, USA. This quarry is now closed and these fossils are very difficult to find. They date back to the Middle Devonian - 345 to 395 million years ago.
Replacement is a fossil preservation process that occurs naturally, replacing the original mineral with another, preserving the original crystal shape.
You can see the ridges in the shell, with a few solid cracks in the original shell. These are completely hard and not loose.
Color is mostly glittery pyrite gold with small areas of matrix intact
Bottom of Brach is completely pyritized as well.
Silica Formation, Middle Devonian; Quarry in Sylvania area, Lucas County, northwestern Ohio, USA