The beautiful, delicate object often found washed up on a beach is not a shell, but the skeletal remains of a marine animal called a sand dollar. This creature is a type of flattened sea urchin. The smooth, white disc that beachcombers seek is actually the endoskeleton, known as the “test,” which is composed of calcium carbonate plates. Preservation aims to stabilize this fragile, porous structure, ensuring it remains intact as a long-lasting keepsake. This process requires careful handling and specific cleaning steps to transform the brittle natural find into a display-ready artifact.
Identifying a Live Sand Dollar
Distinguishing a live sand dollar from a dead test is the first step for any collector. A living sand dollar is characteristically dark in color, often brown, purple, or a reddish-brown hue, which helps it camouflage on the seabed. This coloration is a clear indicator that the organism still possesses its living tissue and pigment.
The surface of a live specimen is covered in dense, fine spines, which give it a soft, velvety appearance and texture. These spines, along with microscopic hairs called cilia, are constantly moving and help the sand dollar bury itself, move, and transport food particles to its mouth. If you gently touch a dark-colored specimen and see any subtle movement of this velvety coat, the animal is alive and should be left undisturbed.
In contrast, the collectible test is bleached white, pale gray, or tan, having lost all its original color after the creature’s death. The spines and cilia fall off quickly, leaving behind a smooth, hard, and brittle structure. A dead test will exhibit no movement whatsoever and often has a fragile, sun-dried appearance, frequently found higher on the beach, away from the water line.
Ethical and Legal Considerations for Collection
Collecting live marine creatures, including sand dollars, is illegal in many coastal jurisdictions, and fines may be imposed. These laws exist to protect the marine ecosystem, where sand dollars play a significant role. They are deposit feeders, consuming detritus and microscopic organisms in the sand, helping to clean the ocean floor.
They are also a food source for other animals, helping maintain the natural balance of the environment. Removing a live specimen disrupts this ecological network and is considered unethical. If a live, dark-colored sand dollar is found stranded on the beach, the responsible action is to gently return it to the shallow water so it can re-bury itself. Only the dead, white, or gray tests, which are essentially the skeletal remains, should be considered for collection and preservation.
The Preservation Process
Once a collected test is secured, the initial preservation step involves thorough cleaning to remove any remaining sand or organic debris. The sand dollar should be soaked in fresh water, which helps flush out matter from inside the porous structure. The water may become cloudy as this organic material is released, requiring the water to be changed repeatedly until it remains completely clear after several hours of soaking.
To achieve the classic white appearance and sanitize the test, a diluted bleach solution is used for a brief period. A common ratio is mixing equal parts of household bleach with water, or one part bleach to three parts water. The sand dollar should be submerged in this mixture for no more than 10 to 20 minutes, as prolonged exposure can weaken the fragile calcium carbonate structure and cause it to disintegrate.
After the short bleach soak, immediately remove the sand dollar and rinse it thoroughly under running fresh water to neutralize the corrosive bleach. Failure to completely remove the bleach residue can lead to a yellow discoloration developing over time. The clean test must then be allowed to air dry completely, ideally placed on a cooling rack in a sunny spot to aid the drying process and enhance the whitening effect.
The final step is hardening the brittle test to prevent it from breaking during display or handling. Create a strengthening solution by mixing equal parts of white craft glue and water. This thin mixture is then carefully painted onto the entire surface using a soft-bristled paintbrush, starting with one side and allowing it to dry fully before flipping it over. The glue solution soaks into the pores, creating an invisible protective layer that significantly increases the structural integrity of the delicate test, preparing it for safe and long-term display.