These little fossil gastropods/snails are usually found as part of an agate conglomerate called turritella or rattlesnake agate. The species is not Turritella, but is actually goniobasis. Some of them will have the external shell intact, some will only be the internal cast, and others will be anything in between the two. All are interesting to study.
They belong to the Phylum: Mollusca, Class: Gastropoda, Order: Mesogastropoda, Family: Turritellidae, and Species: goniobasis.
They are sold in lots of 100 pieces for $10.00 ($.10 per piece).
goniobasis - gastropod/snail 
Quantity in Basket: None
Code: BF-100
Price: $10.00
Shipping Weight: 0.86 pounds
Time: Eocene, approximately 40 million years ago.
Location: Texas, Wyoming, and other.