sounds like something is hitting a fan???

my dishwasher is making a funny sound, like if you were to put a pen or pen like object in a fan?? I hope i'm explaining this correctly. It's really annoing. I'm if the "spinner" is hitting something.
we did find a broken black piece of plastic on the bottom. i'm wondering if this has anything to do with it?

can someone help me diagnose this?

thanks