Monasteries and convents are common in Bhutan. Both monks and nuns keep their heads shaved and wear distinguishing maroon robes. Their days are spent in study and meditation but also in the performance of rituals honoring various bodhisattvas, praying for the dead, and seeking the intercession of bodhisattvas on behalf of the ill. Some of their prayers involved chants and singing accompanied by conch shell trumpets, trumpets made from human thighbones, metal horns up to three meters .