Holectypoida
# 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 †
