Playa Cazon, Habinsel Samana, Dominican Republic

  The Samana Peninsula is dramatically poised at the intersection of the Caribbean and North American tectonic plates. But, this remarkable sample illustrates contemporary marine diversity off the northeast coast of the Dominican Republic.

  Conical and coiled grains, plus the cross-section, near center, are gastropods. The bivalve lower right is a scallop shell. The deep purple, green and white striated rods are urchin spines. So is the pale green bit, lower left, it retains its socket end where it once attached to the urchin’s calcite skeleton. Lower right, the smooth tan-colored rod is coralline algae. At least three different forams are present including the gray spirals near center and the caramel colored discs lower right. The pink–to-red bits are encrusting forams. The tubes with the tiny grains, top center, are worm cases; to make these, the worms secrete an adhesive to glue the grains together. Look top center at the lower half of the rectangular pinkish fragment and find a glassy three-pronged sponge spicule.

  Note: we use the German spelling for this location as the sample was provided by a German colleague who collected the sand while vacationing there.

 Alexrk2, CC BY-SA 3.0, from Wikimedia Commons