<P> The pigmented layer is generated by the coronet, and its color is just like that of the coronet skin from which it is derived . If the coronet skin has any dark patch, the walls show a parallel pigmented line, from the coronet to the ground, showing the wall's growth direction . This layer has predominately protective role, and is not as resistant to ground contact, where it can break and flake away . </P> <P> The water line is built up by the coronet and by the wall's corium (the living tissue immediately beneath the walls). Its thickness increases proportionally to the distance from the coronet and, in the lower third of the walls, is thicker than the pigmented layer . It is very resistant to contact to the ground, and it serves mainly a support function . </P> <P> The white line is the inner layer of the wall . It is softer and fibrous in structure and light in color; white in a freshly trimmed hoof, yellowish or gray after exposure to air and dirt . From the underside of the healthy hoof, it is seen as a thin line joining the sole and the walls . The white line grows out from the laminar connections . Any visible derangement of the white line indicates some important derangement of laminar connections that fix the walls to the underlying P3 bone . Since the white line is softer than both the walls and the sole, it wears fast where it appears on the surface; it appears as a subtle groove between the sole and the walls, often with some debris or sand inside . </P> <P> The three layers of the wall merge in a single mass and they grow downwards together . If the wall does not wear naturally, from sufficient movement on abrasive terrains, then it will protrude from the solar surface . It then becomes prone to breakage, and the healthy hoof will self - trim, by breaking or chipping off . </P>

What type of hoof does a horse have