Angela Nelson is a Pulitzer Prize-winning digital editor and also storyteller who extended a range of basic interest stories on MNN (now part of from 2014-2019.

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Sand dollars room flat and burrowing invertebrates consisted of in the class of marine pets known as echinoids, or spiny-skinned creatures. They are frequently referred to as "irregular" sea urchins and share much of your anatomy v their globular cousins. They are additionally related to similar radially symmetrical animals, like sea lilies, sea cucumbers, and also sea stars (aka starfish) — return the latter drops into a different class.

4. Lock Have numerous Nicknames

In the U.S., the usual name for the Echinarachnius parma species is "eccentric sand dollar," or simply "sand dollar" because that short. The surname derives native the animal's same to disagreement coins, of course; however, it likewise goes by "sand cake," "sea biscuit," and "cake urchin," or, in brand-new Zealand, "sea cookie" and also "snapper biscuit." In southern Africa, it's often referred to as a "pansy shell" for its flower-like pattern.


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Sand dollars room not picky around their living arrangements. Also though castle have whole oceans at their (virtual) fingertips, they have tendency to stick with each other in pack crowds. The Monterey only Aquarium states as many as 625 can reside in a solitary square garden (or .8 the a square meter). This likely has something to perform with their setting of reproduction. Sand dollars practice "broadcast" or "group" spawning, definition both sexes relax eggs and sperm into the water. The much more there are, the greater the success rate.

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8. Castle Have few Predators

Because sand dollars have tough skeletons and also very couple of edible parts, castle don't have countless predators. A few creatures will accept the challenge of ingesting them, though, together as s pout (eel-like fish through wide, fleshy mouths), California sheepheads, starry flounders, and large pink sea stars. (So, yes, they're even at risk of being preyed top top by their own.)

9. You have the right to Tell a Sand Dollar's period by Its ring

Similar come the way rings ~ above a tree stump symbolize every year of life, so perform the growth rings ~ above the bowl of a sand dollar's test. The number of rings boosts with body size, definition the enlarge the sand dollar, the larger it should be. According to the Monterey only Aquarium, the disk-like, shell-resembling ocean dwellers have the right to live for 6 to 10 years.