No, not quite!  Many of our Native American artists use a type of sea shell called "spiny oyster shell"  also known as "spondylus."  Archaeologists have found evidence for jewelry being made from the shell as early as the Neolithic period, 5000 years ago.  The shell comes in a variety of colors, ranging from red, purple, orange and yellow.  In jewelry, we can  distinguish the shell from other stones (as well as the commonly confused coral) by the white variation found throughout.