These fossil sea urchins are also called sand dollars. It is a group of sea urchins that live at the bottom of the sea once adults. They can only swim freely as larvae, as soon as the round skeleton is formed, the sea urchin remains on the bottom.
Over 66 million years old
These fossil specimens come from the Late Cretaceous and are between 66 and 72.1 million years old. The sea urchins were found in the limestone quarry in Lixhe, Belgium, which is now closed to the public. Characteristic is the light colour and detailed surface of the sea urchin combined with flint deposits.
It is remarkable that the animals are not yet extinct. After hundreds of millions of years, they still exist in our seas in an almost unchanged form.