When Emma first noticed several horizontal grooves crossing her fingernails, she assumed they were nothing more than cosmetic imperfections. She had been doing more cleaning lately, using different products, and had also started getting frequent manicures. Still, the lines seemed unusually consistent. They appeared across several nails at nearly the same level, as though someone had drawn faint marks across them. She searched for possible explanations and quickly found plenty of alarming possibilities. Some sources connected nail changes with illness, nutritional problems, or other health conditions. The more she read, the more concerned she became.

Instead of guessing, Emma decided to observe the changes. She photographed her nails and began checking them every few weeks. She noticed something strange: the grooves were not staying in the same place. As her nails grew, the marks slowly moved toward the tips. She compared one nail with another, then another, and suddenly noticed that the grooves seemed to be separated from the nail beds by surprisingly similar distances. She stared at them for a long moment, remembering something that had happened months earlier. Then she realized when the lines must have formed…