Moon snail egg cases, commonly called sand collars, appear to be thin pieces of rubber in the shape of a round collar. They are composed of snail eggs sandwiched between layers of mucus coated with sand. About half way through the summer, the eggs hatch and the collars fall apart. The free swimming snail larvae become part of the zooplankton in the ocean until they are ready to settle down and transform into little moon snails.-- Photo by Rita Rollins