Atlantic Horseshoe Crab

Not really a crab, and also not even a crustacean, but an animal belonging to a closely related subphylum (The Chelicerata which includes such organisms as spiders, scorpions and ticks).

Horseshoe crabs are living fossils, with the earliest fossils found nearly 450 million years ago.

They come onshore in large numbers along the Atlantic coast to breed. This individual was recently deceased upon the shore and is well over a foot (300 cm) long.