The sand dollar is the common name for a marine animal in the same phylum as the starfish. It has a rigid, flattened, disk-shaped test, or shell, made of firmly united plates lying just beneath the thin skin. Small spines that densely cover the test enable the animal to burrow in sand just below the surface.
Sand dollars are classified in the phylum Echinodermata, class Echinoidea, order Clypeastroida. Echinoderms are divided into five classes: Class Crinoidea (sea lilies); Class Asteroidea (starfish); Class Ophiuroidea (brittle stars); Class Echinoidea (sea urchins and sand dollars); and Class Holothuroidea (sea cucumbers).
I have long regarded sand dollars as talismans. To me, they are worth more than any currency. Steven suggested I soak them in bleach or dry them in the sun. But I'm in no rush to turn them white. I like them just as they are.