sand dollar

noun

sand dollar

noun

1

Any echinoderm of the order Clypeasteroida, having a flat, disk-shaped body with the mouth in a mid-ventral position, and living in sand, on or near the surface.

In the sand dollars, the arrangement of the food grooves and consequently the lateral water vessels and their accessory tube feet is more complex (Phelan 1977).1987, John M. Lawrence, chapter I, in A Functional Biology of Echinoderms, page 75:
Adult echinoderms have a five-part body plan corresponding to the arms of a sea star or the design on the "shell" of a sand dollar.2000, Sandra Alters, chapter I, in Biology: Understanding Life, page 692:

1 more example

If you look carefully, a sand dollar is merely a sea urchin in flattened form.2001, Jennifer Hahn, Spirited Waters: Soloing South Through the Inside Passage, published 2009, page 135:

Derived terms: Bahamian sand dollar, eccentric sand dollar, keyhole sand dollar

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.