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What Is Inside a Sand Dollar?

The "Doves of Peace" Inside a Sand Dollar

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Sand Dollar

The "dove" from inside a sand dollar.

Saylah Rossman, Flickr Sand Dollar Tests/emmadiscovery, Flickr

Sand Dollar Tests

emmadiscovery, Flickr

Have you ever walked along the beach and found a sand dollar shell?  This shell is actually called a test, and is the endoskeleton of the animal - what's left behind after the sand dollar dies and its spines fall off. The test may be white or grayish in color, and has a star-shaped marking in its center.

If you pick up the test and shake it gently, you may hear rattling inside.  What is inside?

The Legend of the Sand Dollar

Visit a shell shop and you may find poems or plaques illustrating the Legend of the Sand Dollar, often with a sand dollar to accompany them. The author of the poem is apparently unknown. But one part of it says, 

Now break the centre open
And here you will release
The five white doves awaiting
To spread Good Will and Peace.

The five white "doves" are parts of the sand dollar's mouth. The mouth of a sand dollar, and other urchins, is called the Aristotle's lantern. This apparatus was described by Greek philosopher and scientist Aristotle, who said it resembled a horn lantern, which was a 5-sided lantern made of thin pieces of horn. The 5 parts of the Aristotle's lantern are five jaws, which are part of an amazing eating apparatus made up of the jaws, plus muscles and connective tissue - about 50 skeletal elements and 60 muscles in all.

When a sand dollar dies and dries up, the Aristotle's lantern may break up into the five "doves" of legend, and create that rattling sound you hear when you shake a sand dollar test.

References and Further Information

  1. About.com
  2. Education
  3. Marine Life
  4. Marine Life Profiles
  5. Invertebrates
  6. What Is Inside a Sand Dollar?

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