Shell ID help

[hnieman]

Hello all,

I came across a small box full of these shells while cleaning out my grandfather's estate.  All of the shells in the box were the same type which I thought was kind of odd.  I have a small shell collection, but I've never seen these before.  Some of them have nice blue and orange banding.

I thought I'd check to see if you experts can ID these for me.

I just realized that I have nothing in the pic for scale.  Most of them are around two inches long.

<a href="http://www.badongo.com/pic/10335983" target="_blank"><!-- m --><a class="postlink" href="http://www.badongo.com/pic/10335983">http://www.badongo.com/pic/10335983</a><!-- m --></a>