Regular echinoids are recognised from the Ordovician period, epifaunal grazers with spines for protection and movement. Irregular echinoids are recognised from the Jurassic, replacing pentaradial symmetry with bilateral, becoming infaunal deposit feeders, and using smaller more fine spines for burrowing... Read more


  • Phylum: Echinodermata
  • Class: Echinoidea

Diagnostic features

These are the features that will help you to identify fossils as echinoids.

  • Ambulacra (tube feet)
  • Anus
  • Mouth or peristome
  • Pentaradial/bilateral symmetry

Stratigraphic range

Ordovician to present