Polar Bear Hair
Polar bear have black skin. and it's hair are hollow , their fur isn't white , it's transparent , so it appears white as it reflects light.
Polar bear fur isn’t actually white! It’s hollow and made of transparent keratin, with little to no pigmentation. When sunlight hits the bear, it undergoes a complex scattering process within the fur (more on that in a bit), with a small amount of light eventually being reflected. Since the sun’s light is white, it’s the color we perceive polar bears to be.