This is one of Earth's most unfamiliar life forms. Like an earthworm, it spends its entire life buried in a food-rich substrate slowly engulfing what comes to its mouth, digesting the sparse food that it encounters, then excreting what is left from the other end. It is a member of a marine phylum of life containing 7,000 species found in all the seas on Planet Earth.
In my late 20's I lived in Puerto Rico and spent as much time as I could beach-combing and snorkeling in the shallow Caribbean coral reefs. I would encounter bizarre egg-like skeletons at the upper tide level, washed there with the sticks and other flotsam temporarily just out of the reach of the waves. These fragile treasures were as light and insubstantial as cascarónes, the confetti eggs children in Spanish-influenced cultures love to smash on their friends' heads at cumpleaño parties. Most were broken fragments, and the few that were intact had to be handled with caution. Like sand dollars on Texas beaches, they were long-dead relics of organisms that made a meager living just offshore. As a youth, I used to shuffle my toes in the sand at my feet on Gulf beaches between the surf-breaking sandbars in neck-deep waters. When I encountered little rough disks I would wrap my toes around them and reach down with my hand to extract them from between my toes. Unlike the smooth, sun-bleached forms found on the dry beaches, they were tan in color, and covered with tiny bristles that waved about in alarm. Usually, I would give them a toss and look for more, but sometimes I would bring them into sandy tide pools to inspect their habits. I would lay them flat in the calm waters and in seconds they would bury themselves by pulling sand grains up and laying them on their top surface, like pulling the covers up as they put themselves to bed. I would lie down next to the tide pool and place them in the palm of my hand to see how they did this neat little trick. Projecting between the spines waved tiny white arms that seemed to stick to my fingers. The spines acted in unison with these fleshy arms to move them along quite rapidly. Sensing their distress, I would take them back to the quiet waters between the sandbars and drop them back home.
I remembered these sand dollars as I found these marine cascarónes in Puerto Rico and knew that these marine cascarónes were related to the sand dollars since both featured a 5-pointed star symmetry. I began to look for their living representatives and presumed that like sand dollars they could be found in the shallow sand. As I snorkeled in quiet waters I began to dredge my fingers into the sand and was soon rewarded with the grand prize!I brought to the surface a giant 8-inch sea biscuit nearly 2 inches in depth. Like the sand dollar they were covered with short hair-like spines, but also had a few long spines 4 or 5 inches long, which they brandished at me like menacing swords. Like the sand dollars, they too buried themselves when returned to their habitat, though slower due to their great size. Although it violated my "leave-it-alone" philosophy, I took one of these "sea biscuits" as they are commonly called, and dry-landed it to steal its life and skeleton. Once the corruption of the flesh brought on by its death hollowed it out, I rubbed off the spines and soaked it in bleach to render it white in color.
It was so very fragile that I knew I could never add this to my collection of sea urchins and sand dollars that I was bringing together for study. I applied several layers of varnish to strengthen the shell, and was pleased with how strong the result was. I was surprised that this had the side effect of bringing out a pattern of skeletal elements that I had previously seen only the suggestion of. I would learn years later in paleontology classes that the individual ossicles composing the skeleton were single crystals of calcium carbonate. When thin sections of rock samples are subjected to certain kinds of light rays (as geologists are prone to do) these single crystals shone like beacons of their special character.
In my late 20's I lived in Puerto Rico and spent as much time as I could beach-combing and snorkeling in the shallow Caribbean coral reefs. I would encounter bizarre egg-like skeletons at the upper tide level, washed there with the sticks and other flotsam temporarily just out of the reach of the waves. These fragile treasures were as light and insubstantial as cascarónes, the confetti eggs children in Spanish-influenced cultures love to smash on their friends' heads at cumpleaño parties. Most were broken fragments, and the few that were intact had to be handled with caution. Like sand dollars on Texas beaches, they were long-dead relics of organisms that made a meager living just offshore. As a youth, I used to shuffle my toes in the sand at my feet on Gulf beaches between the surf-breaking sandbars in neck-deep waters. When I encountered little rough disks I would wrap my toes around them and reach down with my hand to extract them from between my toes. Unlike the smooth, sun-bleached forms found on the dry beaches, they were tan in color, and covered with tiny bristles that waved about in alarm. Usually, I would give them a toss and look for more, but sometimes I would bring them into sandy tide pools to inspect their habits. I would lay them flat in the calm waters and in seconds they would bury themselves by pulling sand grains up and laying them on their top surface, like pulling the covers up as they put themselves to bed. I would lie down next to the tide pool and place them in the palm of my hand to see how they did this neat little trick. Projecting between the spines waved tiny white arms that seemed to stick to my fingers. The spines acted in unison with these fleshy arms to move them along quite rapidly. Sensing their distress, I would take them back to the quiet waters between the sandbars and drop them back home.
I remembered these sand dollars as I found these marine cascarónes in Puerto Rico and knew that these marine cascarónes were related to the sand dollars since both featured a 5-pointed star symmetry. I began to look for their living representatives and presumed that like sand dollars they could be found in the shallow sand. As I snorkeled in quiet waters I began to dredge my fingers into the sand and was soon rewarded with the grand prize!I brought to the surface a giant 8-inch sea biscuit nearly 2 inches in depth. Like the sand dollar they were covered with short hair-like spines, but also had a few long spines 4 or 5 inches long, which they brandished at me like menacing swords. Like the sand dollars, they too buried themselves when returned to their habitat, though slower due to their great size. Although it violated my "leave-it-alone" philosophy, I took one of these "sea biscuits" as they are commonly called, and dry-landed it to steal its life and skeleton. Once the corruption of the flesh brought on by its death hollowed it out, I rubbed off the spines and soaked it in bleach to render it white in color.
It was so very fragile that I knew I could never add this to my collection of sea urchins and sand dollars that I was bringing together for study. I applied several layers of varnish to strengthen the shell, and was pleased with how strong the result was. I was surprised that this had the side effect of bringing out a pattern of skeletal elements that I had previously seen only the suggestion of. I would learn years later in paleontology classes that the individual ossicles composing the skeleton were single crystals of calcium carbonate. When thin sections of rock samples are subjected to certain kinds of light rays (as geologists are prone to do) these single crystals shone like beacons of their special character.
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