[2] The term "sand dollar" derives from the appearance of the tests (skeletons) of dead individuals after being washed ashore.

In Spanish-speaking areas of the Americas, the sand dollar is most often known as galleta de mar (sea cookie); the translated term is often encountered in English.

In the folklore of Georgia in the United States, sand dollars were believed to represent coins lost by mermaids.

Dead individuals are commonly found with their empty test devoid of all surface material and bleached white by sunlight.

Unlike other urchins, the bodies of sand dollars also display secondary front-to-back bilateral symmetry with no morphological distinguishing features between males and females.

According to World Register of Marine Species: Sand dollars can be found in temperate and tropical zones along all continents.

[6] Sand dollars live in waters below the mean low tide line, on or just beneath the surface of sandy and muddy areas.

[8] Sand dollars frequently gather on the ocean floor, in part to their preference for soft bottom areas, which are convenient for their reproduction.[why?]

When a predator is near, certain species of sand dollar larvae will split themselves in half in a process they use to asexually clone themselves when sensing danger.

This process doubles their population and halves their size which allows them to better escape detection by the predatory fish but may make them more vulnerable to attacks from smaller predators like crustaceans.