For ten points, identify the name for these animals, the only mammals to lay eggs.
The word used to describe them means "single opening."  This single opening is what zoologists call the cloaca, a duct at the end of the urinary and reproductive system of these creatures. All living members of the order are native to New Guinea or Australia, such as the duck-billed platypus or the echidna. For ten points, identify the name for these animals, the only mammals to lay eggs.
The word used to describe them means "single opening."  This single opening is what zoologists call the cloaca, a duct at the end of the urinary and reproductive system of these creatures.
{Monotreme}s