Echinoid fossils are the fossilised remains of

sea urchin Sea urchins or urchins () are echinoderms in the class (biology), class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body cove ...

s, spiny marine invertebrates that live on the seabed. Humans have been interested in these fossils for millennia, have considered them lucky, have imbued them with magical powers and linked them to their

deities A deity or god is a supernatural being considered to be sacred and worthy of worship due to having authority over some aspect of the universe and/or life. The ''Oxford Dictionary of English'' defines ''deity'' as a God (male deity), god or god ...

Echinoid fossils

The main feature of echinoid fossils is the set of five ambulacra on the

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film) ...

radiating out from a central point, forming a distinctive five-petalled pattern. The earliest echinoid fossils date from the late

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

period, some 450 Mya. The group has a rich fossil record, their hard tests made of

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

plates and their spines being found in rocks from every period since then. Echinoids from the

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

era had thin tests and their fossils are often incomplete, consisting of groups of plates or isolated spines. Later echinoids had more robust tests and fossilised well, usually with the spines detached from the test. Fossils of echinoids are common in rocks from the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

age, especially from late Cretaceous

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...

. In the

White Cliffs of Dover The White Cliffs of Dover are the region of English coastline facing the Strait of Dover and France. The cliff face, which reaches a height of , owes its striking appearance to its composition of chalk accented by streaks of black flint, depo ...

in southern England, the echinoid fossils that are present can be used for

dating Dating is a stage of Romance (love), romantic relationships in which individuals engage in activity together, often with the intention of evaluating each other's suitability as a partner in a future intimate relationship. It falls into the cate ...

the various chalk strata in which they occur. This is because they are relatively abundant and well-preserved compared to other fossilised animals and can be differentiated by type between different ages.

Use in culture

Humans have long had a propensity for collecting fossil echinoids, and these fossils are often found at archaeological sites. The fossils played a part in both Celtic and Norse mythology, were venerated, associated with burials, woven into myths and legends and used when making tools and decorative objects. These fossils are commonly known as thunderstones, fairy loaves or shepherds' crowns. Echinoid fossils are sometimes found associated with archaeological sites. The earliest known example in England is an

Acheulean Acheulean (; also Acheulian and Mode II), from the French after the type site of Saint-Acheul, is an archaeological industry of stone tool manufacture characterized by the distinctive oval and pear-shaped "hand axes" associated with ''Homo ...

hand axe A hand axe (or handaxe or Acheulean hand axe) is a Prehistory, prehistoric stone tool with two faces that is the longest-used tool in human history. It is made from stone, usually flint or chert that has been "reduced" and shaped from a larger ...

from the Middle

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

found in

Kent Kent is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Essex across the Thames Estuary to the north, the Strait of Dover to the south-east, East Sussex to the south-west, Surrey to the west, and Gr ...

. The craftsman had evidently chosen to use this flint for his tool; the exposed area around the sea urchin's jaws known as Aristotle's lantern are clearly visible. Similar examples are known from France, Western and Central Europe, and Northern Africa; they span

Paleolithic The Paleolithic or Palaeolithic ( years ago) ( ), also called the Old Stone Age (), is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehist ...

Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...

Bronze Age The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...

and

Iron Age The Iron Age () is the final epoch of the three historical Metal Ages, after the Chalcolithic and Bronze Age. It has also been considered as the final age of the three-age division starting with prehistory (before recorded history) and progre ...

times.

References

{{Reflist Fossils Echinoidea