Edrioasteroidea

fossil echinoderm class

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June 26, 2026

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The Edrioasteroidea were an extinct class of echinoderms, belonging to the subphylum Pelmatozoa. These marine animals had a plated but flexible body that resembled a sac. The name "Edrioasteroidea" comes from Greek words meaning "sedentary" or "stationary," reflecting their lifestyle. While the fossil record of echinoderms is extensive, many questions remain about their early evolution, with scientists speculating that early forms may have lacked a calcite skeleton, thus not fossilizing.12

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echinoderm
Annotated classification
†Class Edrioasteroidea Lower Cambrian to Lower Carboniferous about 340,000,000–570,000,000 years ago; discoid to cylindrical; 5 well-developed straight or curved ambulacral food grooves radiate from a central mouth. †Class Edrioblastoidea Middle Ordovician about 375,000,000 years ago; stalked form with spheroidal theca; 5 well-developed food grooves.
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†Class Edrioasteroidea Lower Cambrian to Lower Carboniferous about 340,000,000–570,000,000 years ago; discoid to cylindrical; 5 well-developed straight or curved ambulacral food grooves radiate from a central mouth. †Class Edrioblastoidea Middle Ordovician about 375,000,000 years ago; stalked form with spheroidal theca; 5 well-developed food grooves.
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