Sea urchin from the lithographical limestone of Solnhofen

The sea urchin was already roughly prepared - I did the fine preparation work and some finishing on the matrix

The sea urchin was already roughly prepared
I did the fine preparation work and
some finishing on the matrix

Using fine air-abrasives, the surface of the shell can be cleaned quite well

Using fine air-abrasives, the
surface of the shell can be cleaned
quite well

After finishing the preparation on the sea urchin, the matrix can be filled up -
surprisingly, there was a third spine hidden under the rock, which shows magnificent secondary spines (lower left)

After finishing the preparation on the sea urchin,
the matrix can be filled up - surprisingly, there was a third
spine hidden under the rock, which shows magnificent
secondary spines (lower left)

The result after 12 hours of painstaking preparation work

A fully intact, big sea urchin of the genus Rhabdocidaris is quite a rarity when found in the lithographical limestone of Solnhofen. Depending on the condition of the layer, the hardness of the matrix differs and partly is even silicified, which poses quite a challenge while preparing the piece. This specimen came to me already glued and with some initial preparation work already done and so I took to finishing the preparation.

Luckily in this case the matrix was relatively soft and was more or less easy to sand blast. This made it possible to gently clean the preserved secondary spines and shell surface and preserve their details. Fortunately additional spines were found during the preparation, showing quite distinct secondary spines. This commissioned work was done for trifoss.com – here you will find authentic fossils of high quality.

Fossil: Rhabdocidaris orbignyana

Locality: Painten (Germany)

Formation: Late Jurassic, Kimmeridge

Diameter of the sea urchin: 10 cm

Work required: 12 hours