Prime Hook Beach, whose name derives from the Dutch "Priume Hoek" meaning Plum Point, was named by European settlers in the 17th century for the land's abundance of purple beach plums. Beginning in 2007, Prime Hook Beach property owners organized a community effort that grew from beachfront owners to off-beachfront owners and formed the Horseshoe Crab Community of Prime Hook Beach to prevent the harvesting of horseshoe crabs on this critical spawning beach. In 2009, the community became an ERDG Community Horseshoe Crab Sanctuary to help ensure the horseshoe crab cycle continues for future generations. Along these beaches, especially in May and June, stranded horseshoe crabs may be found overturned by the surf and can be helped by gently turning them from the side of the shell rather than by the tail. Horseshoe crabs are an ancient species whose closest ancestor is probably the trilobite, and the horseshoe crab as known today has inhabited the oceans for 450 million years, predating birds and dinosaurs. Of the horseshoe crab species worldwide, the Atlantic horseshoe crab, Limulus polyphemus, is the most numerous and makes up the largest share of the global population. It lives along the eastern coast of North and Central America, but Delaware Bay is the epicenter of its spawning and population because the bay's sandy, wave-protected beaches provide optimal spawning conditions and its tidal flats support juvenile growth and development. Each spring, as many as a million migratory shorebirds gather in Delaware Bay to feed on horseshoe crab eggs and rebuild energy reserves before continuing northward, with at least 11 species relying on the eggs as their primary food during a two- to three-week stopover. The eggs eaten by birds are mainly those brought to the surface by wave action, which otherwise would dry up and never develop, so this feeding has limited effect on the horseshoe crab population. Horseshoe crab blood contains a copper-based clotting factor that detects gram-negative disease-causing bacteria, and the biomedical product derived from it, called LAL, is used to screen all injectable medicines and implanted medical devices for bacterial contamination. In May and June, adult horseshoe crabs return from deeper waters to spawn on protected beaches in bays and coves, with peak spawning on evening high tides during new and full moons. During spawning, clusters form at the water's edge, with as many as 12 satellite males around one female, which burrows into the sand and lays masses of green eggs that the surrounding males fertilize. A female returns on successive tides, laying as many as four to seven egg clusters with each tide, and each cluster, incubating five to eight inches below the surface, contains about 4,000 eggs; a female typically lays about 25 egg clusters each year. Horseshoe crabs seen during spawning are fully adult, reaching sexual maturity about halfway through a twenty-year lifespan, so anything affecting them during spawning can influence the population for years to come. Under optimal conditions, fertilized eggs hatch in about 14 days. Juveniles generally spend their first and second summers on intertidal flats, feeding before daytime low tide and burrowing into the sand for the rest of the day. To grow, horseshoe crabs molt and shed their shell several times in the first year, though they remain small at about 1/2 inch wide, and by age three or four they molt only once a year during July and August. As they age, they move to deeper waters with a larger food supply, continue molting annually until sexual maturity, and then begin their yearly spring migration back to spawning beaches.