A catenoid is a three-dimensional shape made by rotating a catenary curve around the x axis.
A catenoid is one of several types of minimal surfaces.
A physical model of a catenoid can be formed by dipping 2 circles into a soap solution, (popping any film in the center of the circle), and slowly drawing the circles apart.
One can make a continuous and isometric deformation of a catenoid to a helicoid such that every member of the deformation family is minimal.