3 shells I need identified

[decipher_bass]

I recently went on a marine biology trip and for our homework we need to make scrapbook pages, and one of my pages i have to identify three shells i found in the Bahamas.  They were all found in the Exhumas in the Bahamas.  I have two gastropods and one bivalve.  The pictures arent so great which will make precise identificiation tough, but really all i need is a rough identification.  I would really appreciate any help with these.  I havent been able to find anything on the internet to help me identify them.

Univalve
<a href="http://photos-081.ll.facebook.com/photos-ll-sf2p/v74/227/100/1433490081/n1433490081_30030250_3240.jpg" target="_blank"><!-- m --><a class="postlink" href="http://photos-081.ll.facebook.com/photos-ll-sf2p/v74/227/100/1433490081/n1433490081_30030250_3240.jpg">http://photos-081.ll.facebook.com/photo ... 0_3240.jpg</a><!-- m --></a>

Bivalve
<a href="http://photos-081.ll.facebook.com/photos-ll-sf2p/v74/227/100/1433490081/n1433490081_30030252_4341.jpg" target="_blank"><!-- m --><a class="postlink" href="http://photos-081.ll.facebook.com/photos-ll-sf2p/v74/227/100/1433490081/n1433490081_30030252_4341.jpg">http://photos-081.ll.facebook.com/photo ... 2_4341.jpg</a><!-- m --></a>

Univalve
<a href="http://photos-081.ll.facebook.com/photos-ll-sf2p/v74/227/100/1433490081/n1433490081_30030265_2923.jpg" target="_blank"><!-- m --><a class="postlink" href="http://photos-081.ll.facebook.com/photos-ll-sf2p/v74/227/100/1433490081/n1433490081_30030265_2923.jpg">http://photos-081.ll.facebook.com/photo ... 5_2923.jpg</a><!-- m --></a>