TMI- I'm sorry but I'm curios

Was having really painful cramps,  Advil would not cut it the next day got up to use restroom and this came out. I don't know what it was I took it to my doctor they were going to send it for lab testing and in the midst of getting it there they lost my sample. Now I will never know wtf that was it was a pretty  big size. Has this ever happened to anybody?