To view a very informative and interactive infographic that outlines all different nail shapes and abnormalities and their possible causes, please click here. Image Source: http://3.bp.blogspot.com/-GgLKK2A4j2A/U9pJV0f-V4I/AAAAAAAAQlM/KdrZGY-uwsw/s1600/ridges-nails-final.jpg
Your moons, or lunula, are related to your Iodine levels. Low moons, small moons, or no moons indicate low iodine. Info on how to Properly supplement Iodine on this link (not my website, just good info with no sales).