Any ideas on what this is?
I've had it since around December, when it had just started on my right pinky and right thumb. Since then it has spread to all but 3 fingers. It is very gradual, it starts with the half moon kind of disappearing. It then grows out with the nail from the base (not the half moon, the "condition").

It doesn't hurt at all and the nails still grow. Other than being unsightly and having weak nails it doesn't bother me. Although my right thumbnail is kind of crumbly.