Ezekiel 10:9-11

9And when I looked, behold the four wheels by the cherubims, one wheel by one cherub, and another wheel by another cherub: and the appearance of the wheels was as the colour of a beryl stone.

10And as for their appearances, they four had one likeness, as if a wheel had been in the midst of a wheel.

11When they went, they went upon their four sides; they turned not as they went, but to the place whither the head looked they followed it; they turned not as they went.