The sloth has a rough and straw-like fur. Each single hair has deep long grooves. Because it rains daily, green algae grow on the hair ends and between the grooves.
This is the reason why the grayish brown fur develops a green look. This combination serves the sloth as a perfect camouflage.
The sloth also enjoys licking on the algae and gets many vitamins this way, which keeps him in good health.