The Espolla Lagoon

The Espolla lagoon is a singular aquatic system in Catalonia. It does not permanently has got water, but has got temporary pond, in other words that is, that a longer o a shorter period remains dry. The water, also, does not come from a river, on the surface, but it does from underground currents. The singularity of this pond is that allows the appearance of the Triops, a few crustaceans that probably are the most ancient living animal species of the Earth.