Solid center

12x12x6x6 with solid center

This emergence of this variant of the 12 x 12 x 6 x 6 segments per ring manhole cover has caused circular crackling in the street asphalt.  This was seen in the street beneath our feet.

Five ringers

Two manhole covers, both with five segmented rings and a center, were seen in the street beneath our feet.

 

8x8x8x8x8 with raised center

That manhole cover has 8 x 8 x 8 x 8 x 8 segments per ring, label with a raised center, and with vent holes in the second ring. 

 

 

12x12x12x6x6 and depressed center

 

This manhole cover has 12 x 12 x 12 x 6 x 6 segments per ring and a depressed center. 

The five rings make them look similar, but counting the segments per ring shows them to be different.

 

Twelves and sixes

 

12x12x6x6 segments and rings cover

 

The layout of the segments, holes, and ridges of this 12x12x6x6 manhole cover could be adapted to a clock face.