Fossil shell of Pithocerithium rubiginosum (height is 1.5 cm) from the Miocene sediments of Nexing in Austria (left) and isolated reddish polyene pigments on calcium fluoride disc (diameter of ...

Remember, "skeletons" include bone, the protein shell of crabs or insects, the sturdy shells of clams ... Which mineral replaces the original is a function of the chemistry of the groundwater. The ...

Here's the story of how a fossil is made. This is an ammonite. Ammonites were once sea creatures with squid-like tentacles and a curly shell like a snail. They lived at the same time as dinosaurs.