Horseshoe Crab: The 300-Million-Year-Old 'Living Fossil' That Outlived Dinosaurs

• The horseshoe crab is a "living fossil" that has remained virtually unchanged for over 300 million years, surviving multiple mass extinctions.
• Its ancient design, including a hard shell, long tail, and legs, has endured, demonstrating that simplicity can be a successful survival strategy.
• These creatures inhabit shallow coastal waters, particularly along North America's Atlantic and Gulf coasts and Southeast Asia's tropical shores.
• Horseshoe crabs possess unique copper-based blue blood containing amebocytes that detect bacterial toxins, crucial for the Limulus Amebocyte Lysate (LAL) test.
• The LAL test is vital for ensuring the safety of vaccines and medical devices, making the horseshoe crab an extraordinary partner in modern medicine.

Why It Matters: The horseshoe crab is a remarkable 'living fossil' whose ancient design and unique blue blood offer critical insights into evolution and modern medicine.