There are three main layers of skin: 1. Epidermis (outermost layer) 2. Dermis 3. Hypodermis The epidermis contains no blood vessels, and is nourished by diffusion from the dermis. read more
This layer does not have the property of shedding off. Birthmarks are present in this layer as birthmarks are caused by overgrowth of blood vessels, melanocytes, smooth muscle, fat, fibroblasts, or keratinocytes. Therefore, birthmark don't go away. read more
Interestingly, the same study found that the squalene oil on shed skin reacts with harmful ozone in houses, offices and aeroplanes, so dust can actually improve the air quality. read more