cystoid

Table of Contents

Introduction References & Edit History Quick Facts & Related Topics

Images

Read Next

Artist interpretation of space asteroids impacting earth and moon. Meteoroids, meteor impact, end of the world, danger, destruction, dinosaur extinct, Judgement Day, Doomsday Predictions, comet

Major Mass Extinctions

Skeleton fossil record of ancient reptiles in stone.

Do Fossil Fuels Really Come from Fossils?

Rusty patched bumble bee (Bombus affinis) photographed in the Midwest in 2017. endangered species insect pollination

What Would Happen If All the Bees Died?

Cook Strait giant weta (Deinacrida rugosa) found on Matiu/Somes Island in the harbour of Wellington, New Zealand. Dec. 17, 2009 insect

Big Bugs and Colossal Crabs: 7 Invertebrates of Unusual Size

The Panamanian Golden Frog is a critically endangered frog which is endemic to Panama.

Extinct in the Wild but Still Around: 5 Plants and Animals Kept Alive by Humans

Discover

Los Angeles Police Department wanted flyer on Elizabeth Short, aka the "Black Dahlia," who was brutally murdered in January 1947. The FBI supported the Los Angeles Police Department in the case, including by identifying Short through her fingerprints that

America’s 5 Most Notorious Cold Cases (Including One You May Have Thought Was Already Solved)

Woman tied to a ducking stool, a method of punishment by means of humiliation, beating, or death. (cucking stool)

8 Unusual Punishments Inflicted on Women Throughout History

A Factory Interior, watercolor, pen and gray ink, graphite, and white goache on wove paper by unknown artist, c. 1871-91; in the Yale Center for British Art. Industrial Revolution England

Inventors and Inventions of the Industrial Revolution

Why Is Ireland Two Countries?

Leonardo da Vinci (1452-1519), Italian Renaissance painter from Florence. Engraving by Cosomo Colombini (d. 1812) after a Leonardo self portrait. Ca. 1500.

10 Famous Artworks by Leonardo da Vinci

An ancient egyptian hieroglyphic painted carving showing the falcon headed god Horus seated on a throne and holding a golden fly whisk. Before him are the Pharoah Seti and the goddess Isis. Interior wall of the temple to Osiris at Abydos, Egypt.

11 Egyptian Gods and Goddesses

The Cheshire Cat is a fictional cat from Lewis Carroll's Alice's Adventures in Wonderland. (Alice in Wonderland)

11 Banned Books Through Time

cystoid

fossil echinoderm

Also known as: Cystoidea

Written and fact-checked by The Editors of Encyclopaedia Britannica

Article History

Related Topics:: Paleozoic Era; fossil; extinction; Echinosphaerites; Crinozoa

See all related content

cystoid, any member of an extinct class (Cystoidea) of primitive echinoderms (animals with a hard, calcareous external skeleton, related to the modern sea lily and starfish) that first appeared during the Middle Ordovician Epoch and persisted into the Late Devonian Epoch (the Ordovician Period began about 488 million years ago, and the Devonian Period ended 359 million years ago). Once diverse and important, the cystoids had saclike bodies that were attached to a stem anchored to the seafloor. Numerous plates covered the body. Some forms are important guide, or index, fossils and thus allow the correlation of sometimes widely separated rock units.

This article was most recently revised and updated by Richard Pallardy.