Rhombifera

fossil echinoderm class

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July 13, 2026

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The Rhombifera were an extinct class of echinoderms, known only as fossils, that lived from the Lower Ordovician to the Upper Devonian periods, approximately 500 to 350 million years ago. These marine invertebrates are characterized by a globular theca (chamber) and unique respiratory structures called rhomboid sets of folds or canals. The Rhombifera are part of the extinct subphylum Blastozoa within the phylum Echinodermata.1

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echinoderm
Annotated classification
†Class Rhombifera Lower Ordovician to Upper Devonian about 350,000,000–500,000,000 years ago; theca globular; respiratory structures rhomboid sets of folds or canals. †Class Diploporita Lower Ordovician to Lower Devonian about 400,000,000–500,000,000 years ago; theca globular; respiratory structures pairs of pores.
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†Class Rhombifera Lower Ordovician to Upper Devonian about 350,000,000–500,000,000 years ago; theca globular; respiratory structures rhomboid sets of folds or canals. †Class Diploporita Lower Ordovician to Lower Devonian about 400,000,000–500,000,000 years ago; theca globular; respiratory structures pairs of pores.
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