Oh yes, it was super real. And ended up being very uncomfortable in the long run for him.The bone was cow pelvis, I believe, and quite real.
To add to this, even if your local marshals allow it, it may not be allowed in chapters you visit.As mentioned, the rules state that you can only get armor points if the armor is made from the following, non-metal materials:
leather, leather scale, padded cloth, naugahide, suede, doeskin, vinyl, heavy canvas, bone, rope and wood.
With that being said, always check with your local marshals if you have any ideas and see if they'll allow it as an alternative material before putting forth the time, effort and money.