What Causes Discharge Of Piece Of Flesh In Periods?

I had my period it was late but that s normal and it wasnt heavy at all had some really bad cramps one day and that is kinda out of the normal for me and then I went To change my tampon and saw this like piece of like flesh it looked like a piece of liver and it was the same color It was a pretty good size too it And im positive it wasn t a blood clot it looked like flesh what does this mean? I ve tried to look it up but can t find a real answer