Happy Horseshoe Crab Day! While the name might suggest otherwise, this arthropod is not a crab but rather a chelicerate and related to arachnids like spiders and scorpions. This amazing species is often called a “living fossil” because its ancestors date back hundreds of millions of years. The anatomical features of the horseshoe crab include a hard exoskeleton, tail called a telson (used for digging and flipping the horseshoe crab over if it finds itself upside down), and 10 eyes located on var