Sea urchins are common in the fossil fauna from Eocene in the south-east of district of Bages. Sometimes, well preserved, lacking just from the spines individuals are isolated by patient erosion, then happily found. However, much more often a limestone rock with plenty of broken pieces, spines and sections is seen when polished by water or artificially cut. If so, the sea urchin fossils stand out in white in a grey limestone. The circles or ellipses of 2-4 cm diameter and 1-2 mm thick correspond to the section of a sea urchin shell.
The fossils of sea urchins don’t distribute evenly, but in groups revealing that some coastal areas of the former, warm sea were favourable to them. The streams of Mura and Talamanca by sant Esteve de Vila-rasa display rock surfaces with many fossils of sea urchins. The pictures 1st and 2nd show the detail of a limestone with sea urchin fossils from the stream of Talamanca. The pictures 3rd and 4th displays the sections of urchins in the limestone stratum that the river Llobregat exposes in El Pont de Vilomara.
[photos Jordi Badia]
- See the article Pedres milionàries (= Milion-year rocks), in Catalan, by Jordi Badia.