What does the half moon at the base of the nails mean?

We may notice it out of the corner of our eye, without paying any attention. However, the little white crescent form at the base of the nail, known as the lunula, is becoming increasingly intriguing. Is it a discreet reflection of our inner state? Above all, should we be concerned when it disappears or changes appearance? The solution can be summarized in a single word: subtlety.