 Horseshoe crabs originate from 450 million years ago; therefore, they are also called as "living fossils".Because of the copper in their blood, which can be extracted to be applied in detecting bacteria, Horseshoe crabs are highly valued in medical aspect.There are two major relics and one historical site found around the Pak Nai area, which are the sand dunes of the Chen's homeland, Wu's homeland and a fortified structure.