What three characteristics make mammals different from any other animal?

1. Mammary glands: Mammals are the only animals that have mammary glands, which produce milk to feed their young.

2. Hair: Mammals are the only animals that have hair, which helps to insulate them and keep them warm.

3. Three middle ear bones: Mammals have three bones in their middle ear, which allows them to hear a wider range of sounds than other animals.