At the Joan Miró Foundation, a contemporary museum on Montjuïc hill in Barcelona, is a fascinatingly deadly piece of art—a fountain of mercury. It’s a simple, almost childlike creation consisting of a single, standing pipe that releases a narrow stream of liquid mercury into a series of curving aluminum troughs. After swirling and sloshing in a couple of basins and steps built along the way, the toxic liquid strikes a paddle like thing before it falls into a circular pool. The liquid striking the paddle causes it to sway as if catching the wind, and the whole contraption moves a series of rods causing an iron pendant to gently flutter. The pendant spells out the word “ALAMADEN”.

Photo credit: Jeremy Brooks/Flickr