Its the hydrosphere. Hope that helped :)
Answer:
Fireflies produce a chemical reaction inside their bodies that allows them to light up. This type of light production is called bioluminescence. When oxygen combines with calcium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme, light is produced.
Mucus traps foreign particles and germs, protecting the body (especially the trachea)
Due, to know life on the moon there would be nothing to mess with the footprint, but the main reason why these footprints are going to last centuries is because "there is no weather." Since how there is no weather on the moon which means no wind there is no factors that could affect the footprint.
Hope this helps!