Weird Bone Structure

2-26-2021:

I was mining a hole with another player for my IG farm that I am making. Some time later I have discovered a bone block on the ground after mining it I discovered more. I decided to mine around it to see what is was and discovered that it looks like some rib structure. I swear that I did not build it and I am not sure what a chance of a player before me placing it. I just thought it was cool because I have never seen something like this before. It is located in a desert biome in my territory that I now own. Its cords are -3629 51 -8896.