Cutis Verticis Gyrata from Reddit

You have Cutis Verticis Gyrata. which is a medical condition usually associated with thickening of the scalp. People show visible folds, ridges or creases on the surface of the top of the scalp. The number of folds can vary from two to roughly ten and are typically soft and spongy.  (Wikipedia)

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Well, I guess this puts the scalp tension theory to bed from tressless