Description

The fossil of the Pseudocidaris Mammosa is one of the ancestors of the current sea urchins. The oldest fossil of the Echinoidea class that has come down to us dates back to the Jurassic period 200-150 Ma.
It is a particularly beautiful collector's fossil to look at, especially when there is such a complete specimen, with an intact central shell and so many spines still around it.
The shell has a diameter of about 17.5mm while the entire group, including spines, reaches a maximum length of 82mm.