Hier ist ein Fossiler Seeigel aus Ried welcher wohl zur Gattung Pseudodiadema zu stellen ist.
Der fossile Seeigel selber misst etwa 10 mm im Druchmesser.

This specimen features a fossil echnoid of the species Acrocidaris nobilis from the Oxfordian stage of Switzerland.

Fossil sea urchin of the species Acrocidaris nobilis from the Oxfordian stage of Switzerland. 

Here is a decorative cluster featuring 10 fossil sea urchins of the species Conulus subrotundus from the classic site in Wüllen.

Here is a beautiful echinoid fossil of the species Dendraster gibbsii from California.

This is a beautiful fossil echinoid of the species Dendraster gibbsii from California.
This fossil echinoid shows some nice manganese dendrites.

This is a fossil echinoid of the species Dendraster gibbsii from California.
 

This is a  fossil see urchin that belongs to the species Discoidea karakaschi it was found on the Crimea, Ukraine (or Russia).

Here is a rare record of a fossil echinoid of the species Discoidea karakaschi from the Crimea.

Here is a echnoid cluster from the chalk of Wüllen with three fossil echnoids of the species Conulus subrotundus and a specimen of the species Echinocorys gravesii.

Here we have detailed specimen of a fossil  See urchin of the soundfull species Laganum depressum from Egypt.

Here is a Fossil See urchin of the species Laganum depressum from Hurghada in Egypt.

This is a small but detailed regular sea urchin which belongs to the genus Phymosoma. 
This fossil echinoid from Painten snows many spines.
These spine  have a longitudinal striated ornamentation

Here is a fossil Solnhofen echinoid from the Painten Site. The fossil Tetragramma is completely preserved with the spines and the Aristotle's lanten.