Skin remains a barrier despite skin cells continually shedding because the shape of a skin cell is a tetrakaidecahedron, a shape proposed in 1887 by Lord Kelvin, which means that it can always form a very tight, cohesive bond with the cells surrounding it, based on mice and mathematical models.

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Skin remains a barrier despite skin cells continually shedding because the shape of a skin cell is a tetrakaidecahedron, a shape proposed in 1887 by Lord Kelvin, which means that it can always form a very tight, cohesive bond with the cells surrounding it, based on mice and mathematical models.