The Diadematidae are a family of sea urchins. Their tests are either rigid or flexible and their spines are long and hollow.
Cidaris is a genus of pencil sea urchins.
Loveniidae is a family of heart urchins in the order Spatangoida.
Coelopleurus is an extant genus of echinoids with fossil records dating back to the Eocene, with remains found in Europe and North America.
The Strongylocentrotidae are a family of sea urchins in the order Echinoida.
Cidaridae is a family of sea urchins in the order Cidaroida.
Spatangus is a genus of heart urchins in the Spatangidae family. The genus is synonymous with the previously recognised genera Prospatangus Lambert, 1902 and Spatagus. There are nine recognised species. The type species is Spatangus purpureus Müller, 1776 by subsequent designation.
Acanthocidaris maculicollis is a species of sea urchin of the family Cidaridae. Their armour is covered with spines. It came from the genus Acanthocidaris and lives in the sea. Acanthocidaris hastingeria was first scientifically described in 1904 by de Meijere.
Aceste ovata is a species of sea urchin of the family Schizasteridae. Their armour is covered with spines. It came from the genus Aceste and lives in the sea. Aceste ovata was first scientifically described in 1907 by Alexander Emanuel Agassiz & Hubert Lyman Clark.
Clypeaster, common name "cake urchins" or "sea biscuits", is a genus of echinoderms belonging to the family Clypeasteridae.
Aporocidaris fragilis is a species of sea urchin of the family Ctenocidaridae. It is well-armoured with spines. It is placed in the genus Aporocidaris and lives in the sea. Aporocidaris fragilis was first scientifically described in 1907 by Alexander Emanuel Agassiz & Hubert Lyman Clark.
Argopatagus planus is a species of sea urchin of the family Macropneustidae. Their armour is covered with spines. It is placed in the genus Argopatagus and lives in the sea. Argopatagus planus was first scientifically described in 1907 by Alexander Emanuel Agassiz and Hubert Lyman Clark, American scientists.
Caenopedina pulchella is a species of sea urchins of the family Pedinidae. Their armour is covered with spines. Caenopedina pulchella was first scientifically described in 1907 by Alexander Emanuel Agassiz and Hubert Lyman Clark.
Centrostephanus asteriscus is a species of sea urchins of the Family Diadematidae. Their armour is covered with spines. Centrostephanus asteriscus was first scientifically described in 1907 by Alexander Emanuel Agassiz & Hubert Lyman Clark.
Chaetodiadema pallidum is a species of sea urchins of the Family Diadematidae. Their armour is covered with spines. Chaetodiadema pallidum was first scientifically described in 1907 by Alexander Emanuel Agassiz and Hubert Lyman Clark.
Chaetodiadema is a genus of sea urchins of the Family Diadematidae. Their armour is covered with spines.
Araeosoma is a genus of deep-sea sea urchins in the family Echinothuriidae.
Aporocidaris is a genus of sea urchins in the family Ctenocidaridae. Several species are found in deep water in circum-Antarctic locations.
Histocidaris is a genus of sea urchins in the family Histocidaridae. Some species are known from the fossil record.
Caenopedina is a genus of sea urchins of the family Pedinidae.
