Below, the a section of the skin (shield) of a 4.5 year old boar sitting on my old quad bike. Note how the shield is probably twice as thick as the tread of the tire. Consistency of the shield is also the same as tire rubber, the shield cannot be bent or flexed anymore than a heavy tire can be flexed manually.
The Boar was killed with a .280 Remington loaded with the 150 grain Scirocco II at 2925fps, range 180 yards. Bullet entered the shoulder/shield, destroyed the vitals, bounced of the offside shield, coming to rest back in the vitals. Retained bullet weight was just over 75 grains.
Below, shield from a lean 2.5-3yr old boar. The skin (bristles) on this one has been singed. The shield of a wild pig consists of cartilage, the same hard tissue you find in ball joints of game.
Below, the shield of a fully mature boar, shot placement rear lungs (rear of shield) to liver, to skin of Paunch. This boar was killed with a 162 grain 7mm A-Max bullet at an impact velocity of around 2600fps.