<p>Fissurella barbadensis (Gmelin, 1791) - posterior view of a Barbados keyhole limpet shell.
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Family Fissurellidae - limpets use their radulae to scrape algae from hard substrates.  They typically occupy rock intertidal shorelines.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a>
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/jsjgeology/16188952691/">Fissurella barbadensis (Barbados keyhole limpet) (San Salvador Island, Bahamas) 3</a>