Wholesale Dried Molted horseshoe crab shells measuring approximately 7 inches up to 9 inches in size and hand selected and photographed groups of horseshoe crabs for those wanting to see exactly what they are buying..  Horseshoe crabs are marine arthropods of the family Limulidae and order Xiphosura or Xiphosuirda, that live primarily in and around shallow ocean waters on soft sandy or muddy bottoms.  They occasionally come onto shore to mate.  They are commonly used as bait and in fertilizer.