The link for this challenge is: https://dailypost.wordpress.com/photo-challenges/structure/
Last year I took the two photos shown below in Sapa, on the Northwest corner of Viet Nam. They show a water-driven mortar and pestle used to pound grains of rice to remove husks. The structure still works but maybe it is now only displayed for tourists to snap pictures.
Water powered mortar and pestle: accumulation.
Water powered mortar and pestle: release.
