acanthus? weather worn shell?

[wil9000]

I would like to ask for help identifying the following 2 shells.
Both are from a box of Murex. The first had a piece of paper in it that said simply "Acanthus", but this hasn't helped.
<a href="http://www.badongo.com/pic/5818009" target="_blank"><!-- m --><a class="postlink" href="http://www.badongo.com/pic/5818009">http://www.badongo.com/pic/5818009</a><!-- m --></a>

<a href="http://www.badongo.com/pic/5818010" target="_blank"><!-- m --><a class="postlink" href="http://www.badongo.com/pic/5818010">http://www.badongo.com/pic/5818010</a><!-- m --></a>

The second looks like a Black Murex to me, but every surface is rounded evenly. It doesn't look weathered to me, just strange.

<a href="http://www.badongo.com/pic/5818011" target="_blank"><!-- m --><a class="postlink" href="http://www.badongo.com/pic/5818011">http://www.badongo.com/pic/5818011</a><!-- m --></a>

<a href="http://www.badongo.com/pic/5818013" target="_blank"><!-- m --><a class="postlink" href="http://www.badongo.com/pic/5818013">http://www.badongo.com/pic/5818013</a><!-- m --></a>

Thank you for your help