Can someone identify this shell?

[kocu2]

HI! I need to know the name of this shell (and maybe a link that talks about it) for a university project and it's quite urgent! So if someone could help me I would very much appreciate it!!
Thank you for your time.

The pictures are:

<a href="http://www.flickr.com/photos/22128783@N02/3517535188/" target="_blank"><!-- m --><a class="postlink" href="http://www.flickr.com/photos/22128783@N02/3517535188/">http://www.flickr.com/photos/22128783@N02/3517535188/</a><!-- m --></a>

<a href="http://www.flickr.com/photos/22128783@N02/3517532688/in/photostream/" target="_blank"><!-- m --><a class="postlink" href="http://www.flickr.com/photos/22128783@N02/3517532688/in/photostream/">http://www.flickr.com/photos/22128783@N ... otostream/</a><!-- m --></a>