What animal lays the largest egg?

The animal that lays the largest egg is the whale shark. However, a whale shark keeps the egg inside its body until the baby is born. Ostriches lay the biggest eggs found on land.

The largest whale shark egg ever recorded measured 12 inches long, 5.5 inches wide and 3.5 inches thick. Whale sharks are ovoviviparous, which means "egg live birth." The eggs are fertilized and remain in the female until the embryos are born.

An ostrich egg measures around 6 inches in diameter. The egg is laid in a communal nest where male and female ostriches take turns sitting until the eggs hatch in 42 to 46 days.