Horseshoe crabs are more closely related to spiders and scorpions than to crabs. They have six pairs of legs, a hard shell that looks like a horse's hoof, and a long tail. Their first pair of legs are very small and are used for putting food into their mouths.

Horseshoe crabs are called a living fossil because there are fossils of almost identical creatures found that are 230 million years old.

The two horseshoe crabs in the picture are upside down.