ClipArt ETC
"Here one cube may be brought into the position of the other by a rotation of 180 degrees about a traid axis, or by reflection across the octrahedral plane which is perpendicular to this axis." -The Encyclopedia Britannica 1910

Interpenetrating Twinned Cubes

"Here one cube may be brought into the position of the other by a rotation of 180 degrees about a traid…