title: Holectypoida
text: # Holectypoida
  
  The Holectypoida are an order of sea urchins related to the sand dollars. The order consists of just two living genera, but was once more diverse.
  
  ## Description and characteristics
  
  In appearance, the living holectypoids are similar to sand dollars, but with less flattened bodies and an oval outline. They also lack the petal-like patterns found on the bodies of sand dollars.
  
  ## Taxonomy
  
  According to World Register of Marine Species :
  
  * family Anorthopygidae Wagner & Durham, 1966b †
  * family Coenholectypidae Smith & Wright, 1999 †
  * family Discoididae Lambert, 1900
  * family Holectypidae Lambert, 1900 †
  