Horseshoe Crabs are commonly known as ‘living dinosaurs’ because their fossils show they lived 445 million years ago, and they have not evolved much in the past 200 million years. They are actually arthropods and not true crabs, which means they are more closely related to spiders and scorpions. Horseshoe crabs are scavengers and will eat detritus, small invertebrates, and leftover food. Supplement their diet with Nutramar Complete Pellets and Gamma meaty Frozen Foods.