Fossils index

Echinoids

Echinoids live in the sea. Their name is derived from echinos (Greek) which means 'hedgehog'. They are also called sea urchins ('urchin' is an old word for a hedgehog).

Kingdom: Animalia
Phylum: Echinodermata
Subphylum: Echinozoa
Class: Echinoidea

Echinoids are related to crinoids and stafish. These often have 5 fold symmetry. Echinoids have a five-pointed star on their back.

Live sea urchin

You can understand their name when you look at a live sea urchin (left). It is covered in spines. However, these spines drop off easily, so the fossils only have the skeleton, called the 'test'.

Echinoid

Timescale: Echinoids have been around for a long time, about 480 million years ago. There are still echinoids alive today.

People have thought that echinoids were eggs. Pliny the Elder might have mentioned them as snakes' eggs (although the description does not sound quite right). Other people called them tortoise eggs turned to stone, and in Kent, they were just called chalk eggs.

In England, echinoids have been called Sugar Loaves, Fairy Loaves, Shepherd's Crowns and Pixies' Helmets. They look rather like small round loaves of bread. They were used as charms to help the baking of bread. It was thought that fairy loaves protected families against witchcraft, so they always have bread. They were once frequently displayed on the windowsills of Sussex cottages as good luck charms, to protect the cottage from being struck by lightning, or for predicting rain (this could be true, as moisture present in the atmosphere may condense on the fossil first). They were also supposed to keep milk fresh. Another name for echicoids was eagle stones, as the marks on them resemble claw marks.

In Denmark, they were thunderstones (like belemnites in England). Crusaders collected Jewstones, which were echinoids from Ancient Judea. They wore them as lucky amulets. Some echinoids are heart-shaped, so people have thought that they were the hearts of children, turned to stone. Another legend says that Balthazar, one of the three Wise Men was following the Star of the Nativity when he met a girl. To remind him of his journey, the star drew itself onto the local rocks!

Here are echinoids of different shapes.

Size: 40mm
Echinoid

Size: 32mm
Echinoid



These echinoid fossils have been worn away or crushed.

Size: 45mm
Echinoid

Size: 32mm
Echinoid



This echinoid is a Nucleites. It dates from the Jurassic period, about 165 million years old. It comes from Buckingham. Size: 30mm

Echinoid



This echinoid fossil has been broken, but you can see its structure.
Top and bottom shown. Size: 28mm
Echinoid stems
Echinoid arms