clypeasteroid

plural clypeasteroids

1. Any echinoderm of the order Clypeasteroida of sand dollars.

   At ordinal levels, in cassiduloids and holectypoids, ambitus is circular, elliptical or oval, while clypeasteroids have a pentagonal to circular type.

   2008, Anis Kumar Ray, Fossils in Earth Sciences, page 217

   2 more examples

   Their living representatives include the sea urchins or 'true' echinoids, the heart-urchins or spatangoids and allied forms, the sand-dollars or clypeasteroids, and the slate-pencil-urchins, or cidaroids.

   2006, Robert Wynn Jones, Applied Palaeontology, page 181

   Their traditional taxonomy, based on skeletal characters, has been largely corroborated by recent molecular phylogenetic analyses with one marked exception: clypeasteroids are not found to be monophyletic.

   2009, Andrew B. Smith, “Sea urchins (Echinoidea)”, in S. Blair Hedges, Sudhir Kumar, editors, The Timetree of Life, page 302

   Synonyms: pansy shell, sand dollar, sea cookie, snapper biscuit