Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are known as sea biscuits. (Related animals include other sea urchins, sea cucumbers, and starfish. ) Sand dollars can also be called "sand cakes" or "cake urchins".

Clypeasteroida. Retrieved November, 05 2021, from en.wikipedia.org/wiki/Sand_dollar.