Washing machine banging, not unbalanced. Left hard dark pieces of something in bottom. What could this be?

-Took everything out when the banging continued after adjusting the load. Found pieces of hard junk in the bottom. Thinking something disintegrated inside of the machine. What could this be?Could be one of the paddles from the inside of the drum (to agitate the clothes) - available from parts retailers and easy to fit - last one I fitted was 拢11 - cheaper than a new washing machine!
Perhaps is usually wash clothes left much of the fiber stay there, need to open, the fiber delve will do