Big ol coop

I was wondering about that too, but it looks like the type of artificial turf they make door mats of. I think the idea is that the chicken lays the egg in the boxes on the other side of the wall and they roll to the 'human' side of the coop to be gathered (note the black rubber bumpers) I wonder if that worked, we always filled our boxes with straw and even put in fake ceramic eggs in some to encourage hens to use them - hens like to add eggs to a nest, not have them disappear immediately.

What is at the bottom of the nest box?