Prehistoric sea urchin genera

Echinocorys is an extinct genus of echinoids that lived from the Late Cretaceous to the Paleocene. The genus belongs to the Holasteridae family. Its remains have been found in Asia, Europe, Australia (Oceania) and North America.

Micraster is an extinct genus of echinoids from the Late Cretaceous to the early Eocene. Its remains have been found in Africa, Antarctica, Europe, and North America. Micraster was an infaunal echinoid living in a burrow below the sediment surface. The test is clearly bilateral and there is a deep anterior groove to take in water containing organic particles to the mouth. The tube feet keep a supply of nutrient-laden water moving into the burrow. The anus has a waste tube behind it.

Hemicidaris is an extinct genus of echinoids that lived from the Middle Jurassic to the Early Cretaceous. Its remains have been found in Africa, Asia, and Europe.

Hardouinia is an extinct genus of echinoids that lived in the Late Cretaceous. Its remains have been found in North America.

Tylocidaris is an extinct genus of sea urchins that lived from the Early Cretaceous to the Eocene. Its remains have been found in Europe and North America.

Phymosoma is an extinct genus of echinoids that lived from the Cretaceous to the Eocene. Its remains have been found in Asia, Europe, and North America. thumb|left|Syngnathid and Phymosoma granulosum fossils at the Geological Museum in Copenhagen

Plegiocidaris is an extinct genus of echinoids that lived from the Triassic to the Early Cretaceous. Its remains have been found in Asia and Europe. It was named by the paleontologist Auguste Pomel.

Archaeocidaris is an extinct genus of echinoid that lived from the Late Devonian to the Late Permian. Its remains have been found in Africa, Europe, and North America. thumb|left|Archaeocidaris plates and spines from the Bird Spring Formation (Carboniferous) exposed in Kyle Canyon, Spring Mountains, southern Nevada.

Temnocidaris is an extinct genus of echinoids that lived from the Late Cretaceous to the Paleocene. Its remains have been found in Europe and North America.