Insistent Doorknocker

This iron gargoyle face holds an iron ring in its mouth. Once per day, when the flat back of the gargoyle face is placed against a wall, floor, or ceiling, it fuses into place, creating a usable door and penetrating the space beyond up to 1 foot as if using passwall. Speaking the command word again ends the passwall effect, returns the surface to its previous doorless shape, and releases the doorknocker from the surface.