🌊🐚 Horseshoe Crab: Ancient Guardian of the Ocean Floor Meet the horseshoe crab—a 450-million-year-old “living fossil” that scuttles across shallow seas. Though it looks like a crab, it’s actually closer to spiders and scorpions, using its ten legs to crush clams and worms around its mouth hidden beneath its body. Its long tail isn’t a weapon but a tool for flipping itself over. With blue blood vital to modern medicine, this ancient survivor plays a crucial role in marine life and human health.