The area around the ounfò often contains sacred objects, such as a pool of water for Danbala, a black cross for Bawon Samdi, and a "pince" (iron bar) embedded in a brazier for Criminel. Sacred trees, known as "arbres-reposoirs", sometimes mark the external boundary of the ounfò, and are encircled by stone-work edging. Hanging from these trees can be found "macounte" straw sacks, strips of material, and animal skulls. Various animals, particularly birds but also some mammal species such as goats, are sometimes kept within the perimeter of the ounfò for use as sacrifices.