This cave is the result of the collapse of ancient karst systems. Subsequently, there have been processes of concretion in certain areas and of refilling with gaps that later underwent other processes of collapse.
The cavity is located on the road between the Vileta cemetery and the Coll des Vent. It is easy to find as it has an entrance very close to the trail. This entrance is a trench that was made to be able to easily remove the plaster from the cavity. In addition to this entrance, it has another natural entrance that gives access to the upper room of the cavity and a ventilation hole that can be reached from the outside through a small trench. It can be easily entered through the entrance to the trench, although it is practically overrun by vegetation where the brambles make access difficult. In this trench, measuring 12.7x2.5 m, you can still find remains of the horse that gives the cavity its name and that was probably used as a draft animal in mining operations. Outside the trench there is a demolition of considerable dimensions and which is another example of the exploitation work that was done in this cavity