i need help identifying this shell

[chastidyllaws]

i have no idea where this shell came from, i know nothing about seashells could you please tell me if this is rare and what kind it is and if it is worth anything, thanks for your help

i am very green to collecting shells have over 150 need help, thank you<a href="http://www.badongo.com/pic/1348285" target="_blank"><!-- m --><a class="postlink" href="http://www.badongo.com/pic/1348285">http://www.badongo.com/pic/1348285</a><!-- m --></a> <a href="http://www.badongo.com/pic/1348300" target="_blank"><!-- m --><a class="postlink" href="http://www.badongo.com/pic/1348300">http://www.badongo.com/pic/1348300</a><!-- m --></a> <a href="http://www.badongo.com/pic/1348312" target="_blank"><!-- m --><a class="postlink" href="http://www.badongo.com/pic/1348312">http://www.badongo.com/pic/1348312</a><!-- m --></a>