The ancient Egyptians built the Great Pyramid of Giza more than 4,500 years ago.

The first jack-o'-lanterns in Ireland were carved from turnips and potatoes, not pumpkins.

Sea otters hold hands while they sleep so they don't drift apart.

Kangaroos can't walk backwards.

Dolphins sleep with one eye open.

Each zebra has its own unique pattern of stripes.

A year on Mercury is just 88 Earth days long.