HERVE CONGE, ISM / SCIENCE PHOTO LIBRARY HERVE CONGE, ISM / SCIENCE PHOTO LIBRARY
Sea urchin fossils. Rock containing two fossils of Dripneus sp. sea urchins. Sea urchins are marine invertebrates, and usually only their shell (test) is preserved during fossilisation. Here, the rows of small raised bumps shows where the sea urchin's spines emerged when it was alive. The earliest sea urchins first appear in the fossil record during the Ordovician period (488-443 million years ago). Fossils appear when rocks form around objects that have been buried in mud or ash. As the rock forms, the shape and anatomy of buried animals or plants can be preserved.
Model release not required. Property release not required.