More help, please

[wil9000]

I have some what I think are Ark shells, and some others, too.
First, Arca zebra?
<a href="http://www.flickr.com/photos/wil9000/4882086423/" target="_blank"><!-- m --><a class="postlink" href="http://www.flickr.com/photos/wil9000/4882086423/">http://www.flickr.com/photos/wil9000/4882086423/</a><!-- m --></a>
<a href="http://www.flickr.com/photos/wil9000/4882693838/" target="_blank"><!-- m --><a class="postlink" href="http://www.flickr.com/photos/wil9000/4882693838/">http://www.flickr.com/photos/wil9000/4882693838/</a><!-- m --></a>
Then, other Arks?
<a href="http://www.flickr.com/photos/wil9000/4882085959/" target="_blank"><!-- m --><a class="postlink" href="http://www.flickr.com/photos/wil9000/4882085959/">http://www.flickr.com/photos/wil9000/4882085959/</a><!-- m --></a>
<a href="http://www.flickr.com/photos/wil9000/4882692048/" target="_blank"><!-- m --><a class="postlink" href="http://www.flickr.com/photos/wil9000/4882692048/">http://www.flickr.com/photos/wil9000/4882692048/</a><!-- m --></a>
Finally, these look Arkish to me, but I may be completely wrong.
<a href="http://www.flickr.com/photos/wil9000/4882084525/" target="_blank"><!-- m --><a class="postlink" href="http://www.flickr.com/photos/wil9000/4882084525/">http://www.flickr.com/photos/wil9000/4882084525/</a><!-- m --></a>
<a href="http://www.flickr.com/photos/wil9000/4882692436/" target="_blank"><!-- m --><a class="postlink" href="http://www.flickr.com/photos/wil9000/4882692436/">http://www.flickr.com/photos/wil9000/4882692436/</a><!-- m --></a>