Shell beads were used quite widely, so many general archaeological or cultural references will mention them.  I was able to do an entire research paper on archaeological significance of mollusks for a class by simply going through the index of each book I could find on Mesoamerican archaeology and looking for shell, conch, etc.  One caution: some archaeologists have interpreted closed bivalve shells as indicating ritual use instead of food use.  However, some bivalves will open when cooked and then close again once they cool.

Shells have some significance in Mesoamerican mythology.  I even found a story in which a wicked king interfered with the shell trade and got overthrown.  Served him right!

    Dr. David Campbell
    "Old Seashells"
    Biology Department
    Saint Mary's College of Maryland
    18952 E. Fisher Road
    St. Mary's City, MD  20686-3001 USA
    [log in to unmask], 301 862-0372 Fax: 301 862-0996
"Mollusks murmured 'Morning!'.  And salmon chanted 'Evening!'."-Frank Muir, Oh My Word!