manhole cover

Here there are detailed images of a manhole cover, that is an iron cover that close a manhole. It is common to be seen along the road or catwalks: when big enough it used by worker to repair damages to water pipe and drain system. As you can see the plate is rusted: the rust is a reddish-brown cover occurred on iron and steel surface when in contact with air and water.

photo -> nature -> water -> manhole cover