Dear David and Aydin,
Thank you for the tips on the traces left by snails scraping the algae off
rock surfaces. I've sent the new information on to the Skolithos listserver
and Ricardo Melchor.
Happy Thanksgiving to the North Americans! (NSR: Is it true that this was
originally a Dutch holiday that the Puritans picked up during their stay in
Leiden during the 1600's?)
Andrew K. Rindsberg
Geological Survey of Alabama