Pickering Beach on Delaware Bay lies at the world's largest spawning ground for horseshoe crabs, an ancient species that has inhabited the oceans for 450 million years and whose Atlantic species is the most numerous worldwide. Along the eastern coast of North and Central America, the epicenter of spawning and population occurs in Delaware Bay, where sandy, wave-protected beaches and tidal flats provide ideal conditions for spawning and juvenile growth. Horseshoe crabs are an important part of the Atlantic coast ecosystem, providing food for migrating shorebirds, supporting fishing, and supplying a copper-based blood product used to screen injectable medicines and implanted medical devices for bacterial contamination. Their population along Delaware Bay has drastically declined in the last two decades, leading Pickering Beach to partner with the Ecological Research & Development Group to become a sanctuary in 2004 where harvesting is prohibited and visitors are encouraged to right stranded crabs that have been flipped upside down by the surf. Each May and June, adults return from deeper waters to protected bays and coves to spawn, with peak spawning on evening high tides during new and full moons; females lay clusters of green eggs in the sand, fertilized by surrounding males, and juveniles later hatch, grow by molting, and move into deeper water until they reach sexual maturity about halfway through a twenty-year lifespan.