One of the most photographed icon among the stones and boulders of Mulao River is the famed Ark Stone. It has been believed that from precolonial era and up until now, the people can hear loud honking of ships even if they are located in the mountainous area of Compostela. It has been the greatest of all their inquiry on how such rock formation has been perfectly mounted and docked on top of smaller rocks. Because it is located in the middle part of the river, the people believed that it served as a ship of unseen beings who travels away from the place.