Shell cleaning help

[jeffiner7]

I recently found some shells on my honeymoon in the Carribean and need some advice on cleaning.  The first is a cowrie that I found while snorkling.  It is dead and has no meat inside of it, but it is encrusted with hard coral. I have always read that you need to be careful when cleaning cowries, but I have never found any advice on how to clean them.  The second is a sea biscuit that was found freshly dead (I had to scrape some of the spines off it).  I imagine that it could be put into a bleach solution, but I do not want to bleach it white and lose it's dark color.  Any advice on cleaning/preserving would be greatly appreciated.  Thanks in advance!!!

Check out the pictures <a href="http://geocities.com/klzimmerman2000/">here</a>. or copy this link <a href="http://geocities.com/klzimmerman2000/" target="_blank"><!-- m --><a class="postlink" href="http://geocities.com/klzimmerman2000/">http://geocities.com/klzimmerman2000/</a><!-- m --></a>