This is the story of the fabric of life, and how every species is interconnected – each one important, no matter how big or small. At its center is the humble horseshoe crab, a creature which has remained virtually unchanged for 350 million years. Its annual spring spawning produces millions of eggs that are the lifeline for a tiny bird called the red knot, which migrates 10,000 miles from South America to the Arctic each year. Scientific and medical communities have discovered that the crab also provides an indispensable testing agent for drugs and vaccines, as well as resources for human optics and burn treatment. But horseshoe crab numbers are plummeting from their new use as bait for the fishing industry, dropping by two-thirds or more since 1990. And the precious pyramid depending on this age-old creature is about to come crashing down.