That is a British Mark I tank that was apparently captured and then used by the Germans. The armor was reasonably effective against small arms but as the photo illustrates, an explosive shell hit was usually the end for those vehicles.
There was a BBC series called "Soldier" some years back. The one showing these tanks and their men had a great re-creation where the guys inside had to wear what looked like Medieval chain link armor dangling from their helmets covering their faces to prevent injuries from small arms fire spalling the armor. It showed splinters of metal flying off the interior walls and bloodying the faces of the crew as the bullets struck, and bulged the thin plate.
One wonders if these guys knew the fate that awaited ihem in these slow moving eggshells?