How do Flat earthers explain manhole covers?

Fun fact: the first man-made object yo orbit the earth was not Sputnik. The first item launched into orbit was a manhole cover placed directly over an underground nuclear text in the American southwest a few months before Sputnik. They had hoped to recover it to see how radioactive it became but they underestimated the blast force.

With interpretive dance.

Sponge bob square pants?