These images are of the Caloceras johnstoni ammonite fossil. It was found on the Somerset coast of Dorset England. Creatures are from the...

Picture of aragonite ammonite shell fossil of a Sphenodiscus sp . The creature existed the late Cretaceous Period Upper Maastrichtian st...

The original aragonite internal shell dissolved and was replaced by opal in these belemnite fossils. They existed the Cretaceous Period. ...