I am trying to identify this shell

[artist1]

Thank you. I got out the camera today and took a photo. Here it is:

<a href="http://www.imagestation.com/picture/sraid225/p20a269db4d926314eb1674321ed9d5b4/e8018ad1.jpg" target="_blank"><!-- m --><a class="postlink" href="http://www.imagestation.com/picture/sraid225/p20a269db4d926314eb1674321ed9d5b4/e8018ad1.jpg">http://www.imagestation.com/picture/sra ... 018ad1.jpg</a><!-- m --></a>

What threw me off in identifying it was the color. Is the depth of color an indication of age or does it have more to do with the type of sediment the shell was buried in?