Moss, mold or algae can be a foe to your roof. While algae aren’t that harmful to your roof, the former two can cause significant damage, if not looked into early in time.
In case you spot moss or mold on your roof, it is pretty likely that your roof might have some moisture accumulated, leading to their growth. It can lead to curling up the shingles, reducing their lives and may also infest deeper into other parts of the roofing system.
Try spraying a mix of chlorine bleach and water on any of the areas of the roof that you find infested with mold or moss. After 15 minutes or so, power washes the mixture off of the roof. This can help remove the infestation from your roof.