Ezekiel 10:9

So He drove the man out; and at the east of the garden of Eden He stationed the cherubim and the flaming sword which turned every direction to guard the way to the tree of life.

Then I looked at the living creatures, and behold, there was one wheel on the earth beside the living creatures, for each of the four of them.

The appearance of the wheels and their workmanship was like the gleam of beryl, and all four of them had the same likeness, their appearance and workmanship being as if one wheel were within another.